fix(production): Review-Findings aus US-P17 beheben

RescheduleNotAllowed Error-Typ statt InvalidStatusTransition(status, status),
Null-Guard für newDate, Controller-Parameter als Enum statt String (verhindert
500 bei ungültigem Status), partielle Datumsangaben als 400 ablehnen,
ORDER BY in findAll() konsistent mit gefilterten Queries.

backend/src/main/java/de/effigenix/domain/production/ProductionOrder.java

@@ -25,7 +25,7 @@ import java.time.ZoneOffset;
  * 10. Only IN_PROGRESS → COMPLETED transition allowed via complete() (Batch must be COMPLETED – enforced by Use Case)
  * 11. Only PLANNED or RELEASED → CANCELLED transition allowed via cancel(reason)
  * 12. CancelledReason is set exactly once during cancel() and must not be blank
- * 13. Reschedule only in PLANNED or RELEASED, new date must not be in the past
+ * 13. Reschedule only in PLANNED or RELEASED, new date must not be null or in the past
  */
 public class ProductionOrder {
 
@@ -196,7 +196,10 @@ public class ProductionOrder {
 
     public Result<ProductionOrderError, Void> reschedule(LocalDate newDate) {
         if (status != ProductionOrderStatus.PLANNED && status != ProductionOrderStatus.RELEASED) {
-            return Result.failure(new ProductionOrderError.InvalidStatusTransition(status, status));
+            return Result.failure(new ProductionOrderError.RescheduleNotAllowed(status));
+        }
+        if (newDate == null) {
+            return Result.failure(new ProductionOrderError.ValidationFailure("newDate must not be null"));
         }
         if (newDate.isBefore(LocalDate.now())) {
             return Result.failure(new ProductionOrderError.PlannedDateInPast(newDate));

backend/src/main/java/de/effigenix/domain/production/ProductionOrderError.java

@@ -50,6 +50,11 @@ public sealed interface ProductionOrderError {
         @Override public String message() { return "Batch '" + batchId.value() + "' is not in COMPLETED status"; }
     }
 
+    record RescheduleNotAllowed(ProductionOrderStatus current) implements ProductionOrderError {
+        @Override public String code() { return "PRODUCTION_ORDER_RESCHEDULE_NOT_ALLOWED"; }
+        @Override public String message() { return "Cannot reschedule production order in status " + current; }
+    }
+
     record ValidationFailure(String message) implements ProductionOrderError {
         @Override public String code() { return "PRODUCTION_ORDER_VALIDATION_ERROR"; }
     }

backend/src/main/java/de/effigenix/infrastructure/production/persistence/JdbcProductionOrderRepository.java

@@ -47,7 +47,7 @@ public class JdbcProductionOrderRepository implements ProductionOrderRepository
     @Override
     public Result<RepositoryError, List<ProductionOrder>> findAll() {
         try {
-            var orders = jdbc.sql("SELECT * FROM production_orders ORDER BY created_at DESC")
+            var orders = jdbc.sql("SELECT * FROM production_orders ORDER BY planned_date, created_at DESC")
                     .query(this::mapRow)
                     .list();
             return Result.success(orders);

backend/src/main/java/de/effigenix/infrastructure/production/web/controller/ProductionOrderController.java

@@ -73,20 +73,26 @@ public class ProductionOrderController {
     public ResponseEntity<List<ProductionOrderResponse>> listProductionOrders(
             @RequestParam(required = false) @DateTimeFormat(iso = DateTimeFormat.ISO.DATE) LocalDate dateFrom,
             @RequestParam(required = false) @DateTimeFormat(iso = DateTimeFormat.ISO.DATE) LocalDate dateTo,
-            @RequestParam(required = false) String status,
+            @RequestParam(required = false) ProductionOrderStatus status,
             Authentication authentication
     ) {
         logger.info("Listing production orders by actor: {}", authentication.getName());
 
         var actor = ActorId.of(authentication.getName());
-        ProductionOrderStatus statusEnum = status != null ? ProductionOrderStatus.valueOf(status) : null;
 
-        var result = (dateFrom != null && dateTo != null && statusEnum != null)
-                ? listProductionOrders.executeByDateRangeAndStatus(dateFrom, dateTo, statusEnum, actor)
-                : (dateFrom != null && dateTo != null)
+        boolean hasDateRange = dateFrom != null && dateTo != null;
+        boolean hasPartialDate = (dateFrom != null) != (dateTo != null);
+
+        if (hasPartialDate) {
+            return ResponseEntity.badRequest().build();
+        }
+
+        var result = hasDateRange && status != null
+                ? listProductionOrders.executeByDateRangeAndStatus(dateFrom, dateTo, status, actor)
+                : hasDateRange
                 ? listProductionOrders.executeByDateRange(dateFrom, dateTo, actor)
-                : (statusEnum != null)
-                ? listProductionOrders.executeByStatus(statusEnum, actor)
+                : status != null
+                ? listProductionOrders.executeByStatus(status, actor)
                 : listProductionOrders.execute(actor);
 
         if (result.isFailure()) {

backend/src/main/java/de/effigenix/infrastructure/production/web/exception/ProductionErrorHttpStatusMapper.java

@@ -58,6 +58,7 @@ public final class ProductionErrorHttpStatusMapper {
             case ProductionOrderError.RecipeNotFound e -> 404;
             case ProductionOrderError.RecipeNotActive e -> 409;
             case ProductionOrderError.InvalidStatusTransition e -> 409;
+            case ProductionOrderError.RescheduleNotAllowed e -> 409;
             case ProductionOrderError.BatchAlreadyAssigned e -> 409;
             case ProductionOrderError.BatchNotCompleted e -> 409;
             case ProductionOrderError.ValidationFailure e -> 400;