refactor: OffsetDateTime-Migration, atomare Batch-Sequenznummern und Quantity.reconstitute-Overload

- LocalDateTime → OffsetDateTime (UTC) in allen Domain-Klassen, JPA Entities, DTOs und Tests
- Liquibase-Migration 017: TIMESTAMP → TIMESTAMP WITH TIME ZONE für bestehende Spalten
- Custom DateTimeProvider für Spring Data @CreatedDate-Kompatibilität mit OffsetDateTime
- Neue Sequenztabelle (016) mit JPA Entity + PESSIMISTIC_WRITE Lock statt COUNT-basierter
  Batch-Nummernvergabe (Race Condition Fix)
- Quantity.reconstitute(amount, uom) 2-Parameter-Overload für bessere Lesbarkeit

backend/src/test/java/de/effigenix/application/inventory/AddStockBatchTest.java

@@ -119,7 +119,7 @@ class AddStockBatchTest {
                 List.of(StockBatch.reconstitute(
                         StockBatchId.generate(),
                         new BatchReference("BATCH-001", BatchType.PRODUCED),
-                        Quantity.reconstitute(new BigDecimal("5"), UnitOfMeasure.KILOGRAM, null, null),
+                        Quantity.reconstitute(new BigDecimal("5"), UnitOfMeasure.KILOGRAM),
                         LocalDate.of(2026, 12, 31),
                         StockBatchStatus.AVAILABLE,
                         Instant.now()

backend/src/test/java/de/effigenix/application/inventory/RemoveStockBatchTest.java

@@ -43,7 +43,7 @@ class RemoveStockBatchTest {
         var batch = StockBatch.reconstitute(
                 batchId,
                 new BatchReference("BATCH-001", BatchType.PRODUCED),
-                Quantity.reconstitute(new BigDecimal("10"), UnitOfMeasure.KILOGRAM, null, null),
+                Quantity.reconstitute(new BigDecimal("10"), UnitOfMeasure.KILOGRAM),
                 LocalDate.of(2026, 12, 31),
                 StockBatchStatus.AVAILABLE,
                 Instant.now()

backend/src/test/java/de/effigenix/application/production/ActivateRecipeTest.java

@@ -15,7 +15,8 @@ import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import java.math.BigDecimal;
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.List;
 import java.util.Optional;
 
@@ -61,7 +62,7 @@ class ActivateRecipeTest {
                 null, new YieldPercentage(85), 14,
                 Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                 RecipeStatus.ACTIVE, List.of(), List.of(),
-                LocalDateTime.now(), LocalDateTime.now()
+                OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC)
         );
     }
 

backend/src/test/java/de/effigenix/application/production/ArchiveRecipeTest.java

@@ -15,7 +15,8 @@ import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import java.math.BigDecimal;
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.List;
 import java.util.Optional;
 
@@ -45,7 +46,7 @@ class ArchiveRecipeTest {
                 null, new YieldPercentage(85), 14,
                 Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                 RecipeStatus.ACTIVE, List.of(), List.of(),
-                LocalDateTime.now(), LocalDateTime.now()
+                OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC)
         );
     }
 
@@ -118,7 +119,7 @@ class ArchiveRecipeTest {
                 null, new YieldPercentage(85), 14,
                 Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                 RecipeStatus.ARCHIVED, List.of(), List.of(),
-                LocalDateTime.now(), LocalDateTime.now()
+                OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC)
         );
         when(authPort.can(performedBy, ProductionAction.RECIPE_WRITE)).thenReturn(true);
         when(recipeRepository.findById(RecipeId.of("recipe-2"))).thenReturn(Result.success(Optional.of(recipe)));

backend/src/test/java/de/effigenix/application/production/GetRecipeTest.java

@@ -14,7 +14,8 @@ import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import java.math.BigDecimal;
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.List;
 import java.util.Optional;
 
@@ -43,7 +44,7 @@ class GetRecipeTest {
                 "Beschreibung", new YieldPercentage(85), 14,
                 Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                 RecipeStatus.ACTIVE, List.of(), List.of(),
-                LocalDateTime.now(), LocalDateTime.now()
+                OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC)
         );
     }
 

backend/src/test/java/de/effigenix/application/production/ListRecipesTest.java

@@ -14,7 +14,8 @@ import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import java.math.BigDecimal;
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.List;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -42,7 +43,7 @@ class ListRecipesTest {
                 null, new YieldPercentage(85), 14,
                 Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                 status, List.of(), List.of(),
-                LocalDateTime.now(), LocalDateTime.now()
+                OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC)
         );
     }
 

backend/src/test/java/de/effigenix/application/production/PlanBatchTest.java

@@ -17,7 +17,8 @@ import org.mockito.junit.jupiter.MockitoExtension;
 
 import java.math.BigDecimal;
 import java.time.LocalDate;
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.List;
 import java.util.Optional;
 
@@ -57,7 +58,7 @@ class PlanBatchTest {
                 null, new YieldPercentage(85), 14,
                 Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                 RecipeStatus.ACTIVE, List.of(), List.of(),
-                LocalDateTime.now(), LocalDateTime.now()
+                OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC)
         );
     }
 
@@ -67,7 +68,7 @@ class PlanBatchTest {
                 null, new YieldPercentage(85), 14,
                 Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                 RecipeStatus.DRAFT, List.of(), List.of(),
-                LocalDateTime.now(), LocalDateTime.now()
+                OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC)
         );
     }
 

backend/src/test/java/de/effigenix/application/production/RecipeCycleCheckerTest.java

@@ -13,7 +13,8 @@ import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import java.math.BigDecimal;
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.List;
 import java.util.Optional;
 
@@ -48,7 +49,7 @@ class RecipeCycleCheckerTest {
                 null, new YieldPercentage(100), 14,
                 Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                 RecipeStatus.DRAFT, ingredients, List.of(),
-                LocalDateTime.now(), LocalDateTime.now());
+                OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC));
     }
 
     private Recipe recipeWithoutSubRecipes(String id) {
@@ -145,7 +146,7 @@ class RecipeCycleCheckerTest {
                 null, new YieldPercentage(100), 14,
                 Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                 RecipeStatus.DRAFT, ingredients, List.of(),
-                LocalDateTime.now(), LocalDateTime.now());
+                OffsetDateTime.now(ZoneOffset.UTC), OffsetDateTime.now(ZoneOffset.UTC));
 
         when(recipeRepository.findById(RecipeId.of("B"))).thenReturn(Result.success(Optional.of(recipeB)));
         when(recipeRepository.findById(RecipeId.of("C"))).thenReturn(Result.success(Optional.of(recipeWithoutSubRecipes("C"))));

backend/src/test/java/de/effigenix/application/usermanagement/AssignRoleTest.java

@@ -13,7 +13,8 @@ import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.HashSet;
 import java.util.Optional;
 
@@ -42,7 +43,7 @@ class AssignRoleTest {
         testUser = User.reconstitute(
                 UserId.of("user-1"), "john.doe", "john@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(), "branch-1", UserStatus.ACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.ACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
         workerRole = Role.reconstitute(RoleId.generate(), RoleName.PRODUCTION_WORKER, new HashSet<>(), "Production Worker");
     }

backend/src/test/java/de/effigenix/application/usermanagement/AuthenticateUserTest.java

@@ -13,7 +13,8 @@ import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.HashSet;
 import java.util.Optional;
 
@@ -45,10 +46,10 @@ class AuthenticateUserTest {
 
         testUser = User.reconstitute(
                 UserId.of("user-1"), "john.doe", "john@example.com", validPasswordHash,
-                new HashSet<>(), "branch-1", UserStatus.ACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.ACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
 
-        sessionToken = new SessionToken("jwt-token", "Bearer", 3600L, LocalDateTime.now().plusSeconds(3600), "refresh-token");
+        sessionToken = new SessionToken("jwt-token", "Bearer", 3600L, OffsetDateTime.now(ZoneOffset.UTC).plusSeconds(3600), "refresh-token");
     }
 
     @Test
@@ -84,7 +85,7 @@ class AuthenticateUserTest {
     void should_FailWithLockedUser_When_UserStatusIsLocked() {
         User lockedUser = User.reconstitute(
                 UserId.of("user-2"), "john.doe", "john@example.com", validPasswordHash,
-                new HashSet<>(), "branch-1", UserStatus.LOCKED, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.LOCKED, OffsetDateTime.now(ZoneOffset.UTC), null
         );
         when(userRepository.findByUsername("john.doe")).thenReturn(Result.success(Optional.of(lockedUser)));
 
@@ -100,7 +101,7 @@ class AuthenticateUserTest {
     void should_FailWithInactiveUser_When_UserStatusIsInactive() {
         User inactiveUser = User.reconstitute(
                 UserId.of("user-3"), "john.doe", "john@example.com", validPasswordHash,
-                new HashSet<>(), "branch-1", UserStatus.INACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.INACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
         when(userRepository.findByUsername("john.doe")).thenReturn(Result.success(Optional.of(inactiveUser)));
 
@@ -143,7 +144,7 @@ class AuthenticateUserTest {
     void should_NotCreateSession_When_UserLocked() {
         User lockedUser = User.reconstitute(
                 UserId.of("user-4"), "john.doe", "john@example.com", validPasswordHash,
-                new HashSet<>(), "branch-1", UserStatus.LOCKED, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.LOCKED, OffsetDateTime.now(ZoneOffset.UTC), null
         );
         when(userRepository.findByUsername("john.doe")).thenReturn(Result.success(Optional.of(lockedUser)));
 

backend/src/test/java/de/effigenix/application/usermanagement/ChangePasswordTest.java

@@ -12,7 +12,8 @@ import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.HashSet;
 import java.util.Optional;
 
@@ -44,7 +45,7 @@ class ChangePasswordTest {
 
         testUser = User.reconstitute(
                 UserId.of("user-123"), "john.doe", "john@example.com", oldPasswordHash,
-                new HashSet<>(), "branch-1", UserStatus.ACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.ACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
 
         validCommand = new ChangePasswordCommand("user-123", "OldPassword123!", "NewPassword456!");

backend/src/test/java/de/effigenix/application/usermanagement/GetUserTest.java

@@ -12,7 +12,8 @@ import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.HashSet;
 import java.util.Optional;
 
@@ -37,7 +38,7 @@ class GetUserTest {
         testUser = User.reconstitute(
                 UserId.of("user-1"), "john.doe", "john@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(), "branch-1", UserStatus.ACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.ACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
     }
 

backend/src/test/java/de/effigenix/application/usermanagement/ListUsersTest.java

@@ -13,7 +13,8 @@ import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.HashSet;
 import java.util.List;
 
@@ -39,12 +40,12 @@ class ListUsersTest {
         user1 = User.reconstitute(
                 UserId.of("user-1"), "john.doe", "john@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(), "branch-1", UserStatus.ACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.ACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
         user2 = User.reconstitute(
                 UserId.of("user-2"), "jane.doe", "jane@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(), "branch-1", UserStatus.ACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.ACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
     }
 

backend/src/test/java/de/effigenix/application/usermanagement/LockUserTest.java

@@ -13,7 +13,8 @@ import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.HashSet;
 import java.util.Optional;
 
@@ -40,7 +41,7 @@ class LockUserTest {
         activeUser = User.reconstitute(
                 UserId.of("user-1"), "john.doe", "john@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(), "branch-1", UserStatus.ACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.ACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
     }
 
@@ -100,7 +101,7 @@ class LockUserTest {
         User lockedUser = User.reconstitute(
                 UserId.of("user-2"), "jane.doe", "jane@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(), "branch-1", UserStatus.LOCKED, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.LOCKED, OffsetDateTime.now(ZoneOffset.UTC), null
         );
         when(authPort.can(performedBy, UserManagementAction.USER_LOCK)).thenReturn(true);
         when(userRepository.findById(UserId.of("user-2"))).thenReturn(Result.success(Optional.of(lockedUser)));
@@ -118,7 +119,7 @@ class LockUserTest {
         User inactiveUser = User.reconstitute(
                 UserId.of("user-3"), "bob", "bob@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(), "branch-1", UserStatus.INACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.INACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
         when(authPort.can(performedBy, UserManagementAction.USER_LOCK)).thenReturn(true);
         when(userRepository.findById(UserId.of("user-3"))).thenReturn(Result.success(Optional.of(inactiveUser)));

backend/src/test/java/de/effigenix/application/usermanagement/RemoveRoleTest.java

@@ -13,7 +13,8 @@ import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.HashSet;
 import java.util.Optional;
 import java.util.Set;
@@ -44,7 +45,7 @@ class RemoveRoleTest {
         userWithRole = User.reconstitute(
                 UserId.of("user-1"), "john.doe", "john@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(Set.of(workerRole)), "branch-1", UserStatus.ACTIVE, LocalDateTime.now(), null
+                new HashSet<>(Set.of(workerRole)), "branch-1", UserStatus.ACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
     }
 

backend/src/test/java/de/effigenix/application/usermanagement/UnlockUserTest.java

@@ -13,7 +13,8 @@ import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.HashSet;
 import java.util.Optional;
 
@@ -40,7 +41,7 @@ class UnlockUserTest {
         lockedUser = User.reconstitute(
                 UserId.of("user-1"), "john.doe", "john@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(), "branch-1", UserStatus.LOCKED, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.LOCKED, OffsetDateTime.now(ZoneOffset.UTC), null
         );
     }
 
@@ -100,7 +101,7 @@ class UnlockUserTest {
         User activeUser = User.reconstitute(
                 UserId.of("user-2"), "jane.doe", "jane@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(), "branch-1", UserStatus.ACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.ACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
         when(authPort.can(performedBy, UserManagementAction.USER_UNLOCK)).thenReturn(true);
         when(userRepository.findById(UserId.of("user-2"))).thenReturn(Result.success(Optional.of(activeUser)));
@@ -118,7 +119,7 @@ class UnlockUserTest {
         User inactiveUser = User.reconstitute(
                 UserId.of("user-3"), "bob", "bob@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(), "branch-1", UserStatus.INACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.INACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
         when(authPort.can(performedBy, UserManagementAction.USER_UNLOCK)).thenReturn(true);
         when(userRepository.findById(UserId.of("user-3"))).thenReturn(Result.success(Optional.of(inactiveUser)));

backend/src/test/java/de/effigenix/application/usermanagement/UpdateUserTest.java

@@ -13,7 +13,8 @@ import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.HashSet;
 import java.util.Optional;
 
@@ -40,7 +41,7 @@ class UpdateUserTest {
         testUser = User.reconstitute(
                 UserId.of("user-1"), "john.doe", "john@example.com",
                 new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW"),
-                new HashSet<>(), "branch-1", UserStatus.ACTIVE, LocalDateTime.now(), null
+                new HashSet<>(), "branch-1", UserStatus.ACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null
         );
     }
 

backend/src/test/java/de/effigenix/domain/inventory/StockTest.java

@@ -266,7 +266,7 @@ class StockTest {
             var id = StockId.generate();
             var articleId = ArticleId.of("article-1");
             var locationId = StorageLocationId.of("location-1");
-            var quantity = Quantity.reconstitute(new BigDecimal("10"), UnitOfMeasure.KILOGRAM, null, null);
+            var quantity = Quantity.reconstitute(new BigDecimal("10"), UnitOfMeasure.KILOGRAM);
             var minimumLevel = new MinimumLevel(quantity);
             var minimumShelfLife = new MinimumShelfLife(30);
 
@@ -606,7 +606,7 @@ class StockTest {
         var batch = StockBatch.reconstitute(
                 StockBatchId.generate(),
                 new BatchReference("BATCH-001", BatchType.PRODUCED),
-                Quantity.reconstitute(new BigDecimal(amount), uom, null, null),
+                Quantity.reconstitute(new BigDecimal(amount), uom),
                 LocalDate.of(2026, 12, 31),
                 status,
                 Instant.now()

backend/src/test/java/de/effigenix/domain/production/BatchTest.java

@@ -8,7 +8,8 @@ import org.junit.jupiter.api.Test;
 
 import java.math.BigDecimal;
 import java.time.LocalDate;
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -187,8 +188,8 @@ class BatchTest {
                     Quantity.of(new BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     PRODUCTION_DATE,
                     BEST_BEFORE_DATE,
-                    LocalDateTime.now(),
-                    LocalDateTime.now()
+                    OffsetDateTime.now(ZoneOffset.UTC),
+                    OffsetDateTime.now(ZoneOffset.UTC)
             );
 
             assertThat(batch.id().value()).isEqualTo("batch-1");

backend/src/test/java/de/effigenix/domain/production/RecipeTest.java

@@ -239,7 +239,7 @@ class RecipeTest {
                     null, new YieldPercentage(85), 14,
                     Quantity.of(new java.math.BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     RecipeStatus.ACTIVE, List.of(), List.of(),
-                    java.time.LocalDateTime.now(), java.time.LocalDateTime.now()
+                    java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC), java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC)
             );
 
             var result = recipe.addIngredient(validIngredientDraft(1));
@@ -322,7 +322,7 @@ class RecipeTest {
                     null, new YieldPercentage(85), 14,
                     Quantity.of(new java.math.BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     RecipeStatus.ACTIVE, List.of(), List.of(),
-                    java.time.LocalDateTime.now(), java.time.LocalDateTime.now()
+                    java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC), java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC)
             );
 
             var result = recipe.removeIngredient(IngredientId.generate());
@@ -376,7 +376,7 @@ class RecipeTest {
                     null, new YieldPercentage(85), 14,
                     Quantity.of(new java.math.BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     RecipeStatus.ACTIVE, List.of(), List.of(),
-                    java.time.LocalDateTime.now(), java.time.LocalDateTime.now()
+                    java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC), java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC)
             );
 
             var result = recipe.addProductionStep(new ProductionStepDraft(1, "Mischen", null, null));
@@ -445,7 +445,7 @@ class RecipeTest {
                     null, new YieldPercentage(85), 14,
                     Quantity.of(new java.math.BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     RecipeStatus.ACTIVE, List.of(), List.of(),
-                    java.time.LocalDateTime.now(), java.time.LocalDateTime.now()
+                    java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC), java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC)
             );
 
             var result = recipe.removeProductionStep(1);
@@ -507,7 +507,7 @@ class RecipeTest {
                     null, new YieldPercentage(85), 14,
                     Quantity.of(new java.math.BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     RecipeStatus.ACTIVE, List.of(), List.of(),
-                    java.time.LocalDateTime.now(), java.time.LocalDateTime.now()
+                    java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC), java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC)
             );
 
             var result = recipe.activate();
@@ -528,7 +528,7 @@ class RecipeTest {
                     null, new YieldPercentage(85), 14,
                     Quantity.of(new java.math.BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     RecipeStatus.ARCHIVED, List.of(), List.of(),
-                    java.time.LocalDateTime.now(), java.time.LocalDateTime.now()
+                    java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC), java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC)
             );
 
             var result = recipe.activate();
@@ -554,7 +554,7 @@ class RecipeTest {
                     null, new YieldPercentage(85), 14,
                     Quantity.of(new java.math.BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     RecipeStatus.ACTIVE, List.of(), List.of(),
-                    java.time.LocalDateTime.now(), java.time.LocalDateTime.now()
+                    java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC), java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC)
             );
             var updatedBefore = recipe.updatedAt();
 
@@ -588,7 +588,7 @@ class RecipeTest {
                     null, new YieldPercentage(85), 14,
                     Quantity.of(new java.math.BigDecimal("100"), UnitOfMeasure.KILOGRAM).unsafeGetValue(),
                     RecipeStatus.ARCHIVED, List.of(), List.of(),
-                    java.time.LocalDateTime.now(), java.time.LocalDateTime.now()
+                    java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC), java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC)
             );
 
             var result = recipe.archive();

backend/src/test/java/de/effigenix/domain/usermanagement/UserTest.java

@@ -7,7 +7,8 @@ import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.*;
 
 import static org.assertj.core.api.Assertions.*;
@@ -25,7 +26,7 @@ class UserTest {
     private PasswordHash passwordHash;
     private Set<Role> roles;
     private String branchId;
-    private LocalDateTime createdAt;
+    private OffsetDateTime createdAt;
 
     @BeforeEach
     void setUp() {
@@ -35,7 +36,7 @@ class UserTest {
         passwordHash = new PasswordHash("$2a$12$R9h/cIPz0gi.URNN3kh2OPST9EBwVeL00lzQRYe3z08MZx3e8YCWW");
         roles = new HashSet<>();
         branchId = "branch-1";
-        createdAt = LocalDateTime.now();
+        createdAt = OffsetDateTime.now(ZoneOffset.UTC);
     }
 
     @Test
@@ -56,9 +57,9 @@ class UserTest {
     @Test
     @DisplayName("should_SetDefaultCreatedAtToNow_When_NullProvidedForCreatedAt")
     void should_SetDefaultCreatedAtToNow_When_NullProvidedForCreatedAt() {
-        LocalDateTime before = LocalDateTime.now();
+        OffsetDateTime before = OffsetDateTime.now(ZoneOffset.UTC);
         User user = User.reconstitute(userId, username, email, passwordHash, roles, branchId, UserStatus.ACTIVE, null, null);
-        LocalDateTime after = LocalDateTime.now();
+        OffsetDateTime after = OffsetDateTime.now(ZoneOffset.UTC);
 
         assertThat(user.createdAt()).isNotNull();
         assertThat(user.createdAt()).isBetween(before, after);
@@ -129,7 +130,7 @@ class UserTest {
     @DisplayName("should_ReturnNewUserWithLastLogin_When_WithLastLoginCalled")
     void should_ReturnNewUserWithLastLogin_When_WithLastLoginCalled() {
         User user = User.create(username, email, passwordHash, roles, branchId).unsafeGetValue();
-        LocalDateTime now = LocalDateTime.now();
+        OffsetDateTime now = OffsetDateTime.now(ZoneOffset.UTC);
 
         User updated = user.withLastLogin(now).unsafeGetValue();
 

backend/src/test/java/de/effigenix/infrastructure/AbstractIntegrationTest.java

@@ -18,7 +18,8 @@ import org.springframework.transaction.annotation.Transactional;
 
 import javax.crypto.SecretKey;
 import java.nio.charset.StandardCharsets;
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.Date;
 import java.util.Set;
 import java.util.UUID;
@@ -102,7 +103,7 @@ public abstract class AbstractIntegrationTest {
         UserEntity user = new UserEntity(
                 UUID.randomUUID().toString(), username, email,
                 BCRYPT_PASS123, roles,
-                branchId, UserStatus.ACTIVE, LocalDateTime.now(), null);
+                branchId, UserStatus.ACTIVE, OffsetDateTime.now(ZoneOffset.UTC), null);
         return userRepository.save(user);
     }
 }

backend/src/test/java/de/effigenix/infrastructure/usermanagement/persistence/mapper/UserMapperTest.java

@@ -7,7 +7,8 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.HashSet;
 import java.util.Set;
 
@@ -29,11 +30,11 @@ class UserMapperTest {
 
     private User domainUser;
     private UserEntity jpaEntity;
-    private LocalDateTime createdAt;
+    private OffsetDateTime createdAt;
 
     @BeforeEach
     void setUp() {
-        createdAt = LocalDateTime.now();
+        createdAt = OffsetDateTime.now(ZoneOffset.UTC);
 
         // Create JPA entity first
         jpaEntity = new UserEntity(
@@ -112,7 +113,7 @@ class UserMapperTest {
     @DisplayName("should_PreserveAllUserFields_When_MappingToEntity")
     void should_PreserveAllUserFields_When_MappingToEntity() {
         // Arrange
-        LocalDateTime lastLogin = LocalDateTime.now();
+        OffsetDateTime lastLogin = OffsetDateTime.now(ZoneOffset.UTC);
         UserEntity sourceEntity = new UserEntity(
                 "user-456",
                 "jane.smith",
@@ -144,7 +145,7 @@ class UserMapperTest {
     @DisplayName("should_PreserveAllEntityFields_When_MappingToDomain")
     void should_PreserveAllEntityFields_When_MappingToDomain() {
         // Arrange
-        LocalDateTime lastLogin = LocalDateTime.now();
+        OffsetDateTime lastLogin = OffsetDateTime.now(ZoneOffset.UTC);
         UserEntity entityWithLastLogin = new UserEntity(
                 "user-789",
                 "bob.jones",

backend/src/test/java/de/effigenix/infrastructure/usermanagement/web/SecurityIntegrationTest.java

@@ -18,7 +18,8 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.MediaType;
 import org.springframework.test.web.servlet.MvcResult;
 
-import java.time.LocalDateTime;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.util.List;
 import java.util.Set;
 import java.util.UUID;
@@ -327,7 +328,7 @@ class SecurityIntegrationTest extends AbstractIntegrationTest {
                 .orElseThrow();
 
         assertThat(auditLog.getTimestamp()).isNotNull();
-        assertThat(auditLog.getTimestamp()).isAfter(LocalDateTime.now().minusMinutes(1));
+        assertThat(auditLog.getTimestamp()).isAfter(OffsetDateTime.now(ZoneOffset.UTC).minusMinutes(1));
     }
 
     @Test