feat(backend): Dokumente und Bilder mit lokalem Datei-Upload (Modul 29)

DocumentsModule (Document: entityType/entityId, Dateiname, MIME-Typ,
Groesse, Speicherpfad, Hochgeladen-von) fuer Bienenstand/Volk/Koenigin/
Durchsicht/Honigcharge. Upload als multipart/form-data (Multer, 10 MB
Limit, MIME-Allowlist jpeg/png/webp/pdf), Speicherung unter
DOCUMENTS_STORAGE_PATH (austauschbar). ARCHITECTURE.md Annahme 7
dokumentiert die Multi-Replica-Einschraenkung ohne geteiltes Volume.

ApiCore-Backend/prisma/schema.prisma

@@ -53,6 +53,7 @@ model User {
   notifications      Notification[]
   queenEvaluations   QueenEvaluation[]
   webhookSubscriptions WebhookSubscription[]
+  documents            Document[]
 
   @@index([role])
 }
@@ -773,3 +774,30 @@ model WebhookSubscription {
 
   @@index([active])
 }
+
+// ---------------------------------------------------------------------------
+// Dokumente und Bilder (Abschnitt 4.28) – v1.x Modul 29
+// ---------------------------------------------------------------------------
+
+enum DocumentEntityType {
+  APIARY
+  COLONY
+  QUEEN
+  INSPECTION
+  HONEY_BATCH
+}
+
+model Document {
+  id               String             @id @default(cuid())
+  entityType       DocumentEntityType
+  entityId         String
+  fileName         String
+  mimeType         String
+  sizeBytes        Int
+  storagePath      String
+  uploadedByUserId String?
+  uploadedByUser   User?              @relation(fields: [uploadedByUserId], references: [id])
+  createdAt        DateTime           @default(now())
+
+  @@index([entityType, entityId])
+}