feat(cli): Stammdaten-TUI mit Master Data API-Anbindung

- Neue Screens: Kategorien, Lieferanten, Artikel, Kunden (jeweils
  Liste, Detail, Anlegen + Detailaktionen wie Bewertung, Zertifikate,
  Verkaufseinheiten, Lieferadressen, Präferenzen)
- API-Client: Resources für alle 4 Stammdaten-Aggregate implementiert
  (categories, suppliers, articles, customers) mit Mapping von
  verschachtelten Domain-VOs auf flache DTOs
- Lieferant, Artikel, Kategorie: echte HTTP-Calls gegen Backend
  (/api/suppliers, /api/articles, /api/categories, /api/customers)
- 204-No-Content-Endpoints (removeSalesUnit, removeSupplier,
  removeCertificate, removeDeliveryAddress, removeFrameContract)
  lösen Re-Fetch des Aggregats aus
- MasterdataMenu, Navigation-Erweiterung, App.tsx-Routing

frontend/packages/api-client/src/resources/suppliers.ts

@@ -0,0 +1,236 @@
+/**
+ * Suppliers resource – Real HTTP implementation.
+ * Endpoints: GET/POST /api/suppliers, GET/PUT /api/suppliers/{id},
+ *   POST /api/suppliers/{id}/activate|deactivate,
+ *   POST /api/suppliers/{id}/rating,
+ *   POST /api/suppliers/{id}/certificates,
+ *   DELETE /api/suppliers/{id}/certificates (with body)
+ *
+ * NOTE: Backend returns domain objects with nested VOs:
+ *   { "id": {"value":"uuid"}, "name": {"value":"string"},
+ *     "address": {"street":"...","houseNumber":"...","postalCode":"...","city":"...","country":"DE"},
+ *     "contactInfo": {"phone":"...","email":"...","contactPerson":"..."},
+ *     "paymentTerms": {"paymentDueDays":30,"description":"..."},
+ *     "certificates": [{"certificateType":"...","issuer":"...","validFrom":"2024-01-01","validUntil":"2026-12-31"}],
+ *     "rating": {"qualityScore":4,"deliveryScore":4,"priceScore":5},
+ *     "status": "ACTIVE", "createdAt":"...", "updatedAt":"..." }
+ * DELETE /api/suppliers/{id}/certificates returns 204 No Content → re-fetch.
+ */
+
+import type { AxiosInstance } from 'axios';
+
+export interface AddressDTO {
+  street: string;
+  houseNumber: string | null;
+  postalCode: string;
+  city: string;
+  country: string;
+}
+
+export interface ContactInfoDTO {
+  phone: string;
+  email: string | null;
+  contactPerson: string | null;
+}
+
+export interface PaymentTermsDTO {
+  paymentDueDays: number;
+  paymentDescription: string | null;
+}
+
+export interface QualityCertificateDTO {
+  certificateType: string;
+  issuer: string;
+  validFrom: string;
+  validUntil: string;
+}
+
+export interface SupplierRatingDTO {
+  qualityScore: number;
+  deliveryScore: number;
+  priceScore: number;
+}
+
+export type SupplierStatus = 'ACTIVE' | 'INACTIVE';
+
+export interface SupplierDTO {
+  id: string;
+  name: string;
+  status: SupplierStatus;
+  address: AddressDTO | null;
+  contactInfo: ContactInfoDTO;
+  paymentTerms: PaymentTermsDTO | null;
+  certificates: QualityCertificateDTO[];
+  rating: SupplierRatingDTO | null;
+  createdAt: string;
+  updatedAt: string;
+}
+
+export interface CreateSupplierRequest {
+  name: string;
+  phone: string;
+  email?: string;
+  contactPerson?: string;
+  street?: string;
+  houseNumber?: string;
+  postalCode?: string;
+  city?: string;
+  country?: string;
+  paymentDueDays?: number;
+  paymentDescription?: string;
+}
+
+export interface UpdateSupplierRequest {
+  name?: string;
+  phone?: string;
+  email?: string | null;
+  contactPerson?: string | null;
+  street?: string | null;
+  houseNumber?: string | null;
+  postalCode?: string | null;
+  city?: string | null;
+  country?: string | null;
+  paymentDueDays?: number | null;
+  paymentDescription?: string | null;
+}
+
+export interface RateSupplierRequest {
+  qualityScore: number;
+  deliveryScore: number;
+  priceScore: number;
+}
+
+export interface AddCertificateRequest {
+  certificateType: string;
+  issuer: string;
+  validFrom: string;
+  validUntil: string;
+}
+
+export interface RemoveCertificateRequest {
+  certificateType: string;
+  issuer: string;
+  validFrom: string;
+}
+
+// ── Backend response shapes (domain objects with nested VOs) ─────────────────
+
+interface BackendAddress {
+  street: string;
+  houseNumber: string | null;
+  postalCode: string;
+  city: string;
+  country: string;
+}
+
+interface BackendContactInfo {
+  phone: string;
+  email: string | null;
+  contactPerson: string | null;
+}
+
+interface BackendPaymentTerms {
+  paymentDueDays: number;
+  description: string | null; // Note: backend field is "description", not "paymentDescription"
+}
+
+interface BackendQualityCertificate {
+  certificateType: string;
+  issuer: string;
+  validFrom: string; // LocalDate → "2024-01-01"
+  validUntil: string;
+}
+
+interface BackendSupplierRating {
+  qualityScore: number;
+  deliveryScore: number;
+  priceScore: number;
+}
+
+interface BackendSupplier {
+  id: { value: string };
+  name: { value: string };
+  address: BackendAddress | null;
+  contactInfo: BackendContactInfo;
+  paymentTerms: BackendPaymentTerms | null;
+  certificates: BackendQualityCertificate[];
+  rating: BackendSupplierRating | null;
+  status: SupplierStatus;
+  createdAt: string;
+  updatedAt: string;
+}
+
+function mapSupplier(bs: BackendSupplier): SupplierDTO {
+  return {
+    id: bs.id.value,
+    name: bs.name.value,
+    status: bs.status,
+    address: bs.address,
+    contactInfo: bs.contactInfo,
+    paymentTerms: bs.paymentTerms
+      ? {
+          paymentDueDays: bs.paymentTerms.paymentDueDays,
+          paymentDescription: bs.paymentTerms.description,
+        }
+      : null,
+    certificates: bs.certificates,
+    rating: bs.rating,
+    createdAt: bs.createdAt,
+    updatedAt: bs.updatedAt,
+  };
+}
+
+// ── Resource factory ─────────────────────────────────────────────────────────
+
+export function createSuppliersResource(client: AxiosInstance) {
+  return {
+    async list(): Promise<SupplierDTO[]> {
+      const res = await client.get<BackendSupplier[]>('/api/suppliers');
+      return res.data.map(mapSupplier);
+    },
+
+    async getById(id: string): Promise<SupplierDTO> {
+      const res = await client.get<BackendSupplier>(`/api/suppliers/${id}`);
+      return mapSupplier(res.data);
+    },
+
+    async create(request: CreateSupplierRequest): Promise<SupplierDTO> {
+      const res = await client.post<BackendSupplier>('/api/suppliers', request);
+      return mapSupplier(res.data);
+    },
+
+    async update(id: string, request: UpdateSupplierRequest): Promise<SupplierDTO> {
+      const res = await client.put<BackendSupplier>(`/api/suppliers/${id}`, request);
+      return mapSupplier(res.data);
+    },
+
+    async activate(id: string): Promise<SupplierDTO> {
+      const res = await client.post<BackendSupplier>(`/api/suppliers/${id}/activate`);
+      return mapSupplier(res.data);
+    },
+
+    async deactivate(id: string): Promise<SupplierDTO> {
+      const res = await client.post<BackendSupplier>(`/api/suppliers/${id}/deactivate`);
+      return mapSupplier(res.data);
+    },
+
+    async rate(id: string, request: RateSupplierRequest): Promise<SupplierDTO> {
+      const res = await client.post<BackendSupplier>(`/api/suppliers/${id}/rating`, request);
+      return mapSupplier(res.data);
+    },
+
+    async addCertificate(id: string, request: AddCertificateRequest): Promise<SupplierDTO> {
+      const res = await client.post<BackendSupplier>(`/api/suppliers/${id}/certificates`, request);
+      return mapSupplier(res.data);
+    },
+
+    // Returns 204 No Content → re-fetch supplier
+    async removeCertificate(id: string, request: RemoveCertificateRequest): Promise<SupplierDTO> {
+      await client.delete(`/api/suppliers/${id}/certificates`, { data: request });
+      const res = await client.get<BackendSupplier>(`/api/suppliers/${id}`);
+      return mapSupplier(res.data);
+    },
+  };
+}
+
+export type SuppliersResource = ReturnType<typeof createSuppliersResource>;