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/migrations/20260823091941_documents/migration.sql

@@ -0,0 +1,23 @@
+-- CreateEnum
+CREATE TYPE "DocumentEntityType" AS ENUM ('APIARY', 'COLONY', 'QUEEN', 'INSPECTION', 'HONEY_BATCH');
+
+-- CreateTable
+CREATE TABLE "Document" (
+    "id" TEXT NOT NULL,
+    "entityType" "DocumentEntityType" NOT NULL,
+    "entityId" TEXT NOT NULL,
+    "fileName" TEXT NOT NULL,
+    "mimeType" TEXT NOT NULL,
+    "sizeBytes" INTEGER NOT NULL,
+    "storagePath" TEXT NOT NULL,
+    "uploadedByUserId" TEXT,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "Document_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "Document_entityType_entityId_idx" ON "Document"("entityType", "entityId");
+
+-- AddForeignKey
+ALTER TABLE "Document" ADD CONSTRAINT "Document_uploadedByUserId_fkey" FOREIGN KEY ("uploadedByUserId") REFERENCES "User"("id") ON DELETE SET NULL ON UPDATE CASCADE;