feat(backend): QR-Code-System (Modul 22)

QrModule mit GET /qr/:entityType/:id.svg fuer colonies (Deep-Link
direkt zu /inspections/new), apiaries, queens, honey-batches und
storage-containers. Nutzt pdfkit-Nachbar qrcode zur SVG-Erzeugung.

ApiCore-Backend/src/qr/qr.service.ts

@@ -0,0 +1,85 @@
+import {
+  Injectable,
+  BadRequestException,
+  NotFoundException,
+} from '@nestjs/common';
+import * as QRCode from 'qrcode';
+import { PrismaService } from '../prisma/prisma.service';
+
+const ENTITY_TYPES = [
+  'colonies',
+  'apiaries',
+  'queens',
+  'honey-batches',
+  'storage-containers',
+] as const;
+type EntityType = (typeof ENTITY_TYPES)[number];
+
+function isEntityType(value: string): value is EntityType {
+  return (ENTITY_TYPES as readonly string[]).includes(value);
+}
+
+@Injectable()
+export class QrService {
+  constructor(private readonly prisma: PrismaService) {}
+
+  async generateSvg(entityType: string, id: string): Promise<string> {
+    if (!isEntityType(entityType)) {
+      throw new BadRequestException(
+        `Unsupported QR entity type: ${entityType}`,
+      );
+    }
+
+    const exists = await this.entityExists(entityType, id);
+    if (!exists) {
+      throw new NotFoundException('Object not found');
+    }
+
+    const frontendOrigin =
+      process.env.FRONTEND_ORIGIN ?? 'http://localhost:3000';
+    const url = `${frontendOrigin}${this.deepLink(entityType, id)}`;
+    return QRCode.toString(url, { type: 'svg', margin: 1, width: 256 });
+  }
+
+  private async entityExists(
+    entityType: EntityType,
+    id: string,
+  ): Promise<boolean> {
+    switch (entityType) {
+      case 'colonies':
+        return (
+          (await this.prisma.colony.findUnique({ where: { id } })) !== null
+        );
+      case 'apiaries':
+        return (
+          (await this.prisma.apiary.findUnique({ where: { id } })) !== null
+        );
+      case 'queens':
+        return (await this.prisma.queen.findUnique({ where: { id } })) !== null;
+      case 'honey-batches':
+        return (
+          (await this.prisma.honeyBatch.findUnique({ where: { id } })) !== null
+        );
+      case 'storage-containers':
+        return (
+          (await this.prisma.storageContainer.findUnique({ where: { id } })) !==
+          null
+        );
+    }
+  }
+
+  private deepLink(entityType: EntityType, id: string): string {
+    switch (entityType) {
+      case 'colonies':
+        return `/inspections/new?colonyId=${id}`;
+      case 'apiaries':
+        return `/apiaries/${id}`;
+      case 'queens':
+        return `/queens/${id}`;
+      case 'honey-batches':
+        return `/honey-batches/${id}`;
+      case 'storage-containers':
+        return `/storage`;
+    }
+  }
+}