feat: add website social link, fix herkunft origin display, GUI backup schedule, and format-based batch numbering

- SiteSettings gains websiteUrl (e.g. online shop link) alongside the
  existing social links, editable in Verwaltung > Automatisierung.
- /herkunft/[lot] now shows the apiary's Standort instead of its internal
  Name (so multiple apiaries at one location read as one origin), adds
  small icons per social link, and surfaces previously-fetched-but-unused
  data (Honigsorte, Abfülldatum, stat cards) to make the page a richer
  customer-facing info page.
- Backup schedule (path/cron/retention) is now also configurable via the
  GUI (Verwaltung > Backup), stored in a new BackupSettings singleton;
  an env var always wins over the GUI value per field, and the scheduler
  reloads its cron job live when GUI settings change.
- New Automatisierung rules let an admin define a format (e.g.
  "WH-{YYYY}-{SEQ:4}") that auto-generates HoneyBatch.batchNumber and
  BottlingBatch.lotNumber on creation, with an atomic per-rule sequence
  counter and a manual reset. Manual entry still works when the rule is
  inactive.

ApiCore-Backend/src/backup/backup-settings.service.spec.ts

@@ -0,0 +1,131 @@
+import { BackupSettingsService } from './backup-settings.service';
+import { PrismaService } from '../prisma/prisma.service';
+import { AuditLogService } from '../audit/audit-log.service';
+
+describe('BackupSettingsService', () => {
+  let service: BackupSettingsService;
+  let prisma: {
+    backupSettings: {
+      findUnique: jest.Mock;
+      create: jest.Mock;
+      update: jest.Mock;
+    };
+  };
+  let auditLog: { record: jest.Mock };
+
+  const existing = {
+    id: 'singleton',
+    storagePath: '/data/backups',
+    cronSchedule: '0 3 * * *',
+    retentionCount: 14,
+    updatedAt: new Date('2026-01-01'),
+  };
+
+  beforeEach(() => {
+    prisma = {
+      backupSettings: {
+        findUnique: jest.fn(),
+        create: jest.fn(),
+        update: jest.fn(),
+      },
+    };
+    auditLog = { record: jest.fn().mockResolvedValue(undefined) };
+    service = new BackupSettingsService(
+      prisma as unknown as PrismaService,
+      auditLog as unknown as AuditLogService,
+    );
+  });
+
+  describe('get', () => {
+    it('returns the existing singleton row', async () => {
+      prisma.backupSettings.findUnique.mockResolvedValue(existing);
+
+      const result = await service.get();
+
+      expect(result).toEqual(existing);
+      expect(prisma.backupSettings.create).not.toHaveBeenCalled();
+    });
+
+    it('creates the singleton row on first access', async () => {
+      prisma.backupSettings.findUnique.mockResolvedValue(null);
+      prisma.backupSettings.create.mockResolvedValue({
+        id: 'singleton',
+        storagePath: null,
+        cronSchedule: null,
+        retentionCount: null,
+        updatedAt: new Date(),
+      });
+
+      const result = await service.get();
+
+      expect(prisma.backupSettings.create).toHaveBeenCalledWith({
+        data: { id: 'singleton' },
+      });
+      expect(result.id).toBe('singleton');
+    });
+  });
+
+  describe('update', () => {
+    it('stores a valid value and records an audit entry', async () => {
+      prisma.backupSettings.findUnique.mockResolvedValue(existing);
+      prisma.backupSettings.update.mockResolvedValue({
+        ...existing,
+        retentionCount: 30,
+      });
+
+      const result = await service.update({ retentionCount: 30 }, 'user-1');
+
+      expect(prisma.backupSettings.update).toHaveBeenCalledWith({
+        where: { id: 'singleton' },
+        data: {
+          storagePath: undefined,
+          cronSchedule: undefined,
+          retentionCount: 30,
+        },
+      });
+      expect(result.retentionCount).toBe(30);
+      expect(auditLog.record).toHaveBeenCalledWith(
+        expect.objectContaining({
+          entityType: 'BackupSettings',
+          action: 'UPDATE',
+          userId: 'user-1',
+        }),
+      );
+    });
+
+    it('clears a string field when given an empty string', async () => {
+      prisma.backupSettings.findUnique.mockResolvedValue(existing);
+      prisma.backupSettings.update.mockResolvedValue({
+        ...existing,
+        storagePath: null,
+      });
+
+      await service.update({ storagePath: '' }, 'user-1');
+
+      expect(prisma.backupSettings.update).toHaveBeenCalledWith({
+        where: { id: 'singleton' },
+        data: {
+          storagePath: null,
+          cronSchedule: undefined,
+          retentionCount: undefined,
+        },
+      });
+    });
+
+    it('leaves fields untouched when omitted from the dto', async () => {
+      prisma.backupSettings.findUnique.mockResolvedValue(existing);
+      prisma.backupSettings.update.mockResolvedValue(existing);
+
+      await service.update({}, 'user-1');
+
+      expect(prisma.backupSettings.update).toHaveBeenCalledWith({
+        where: { id: 'singleton' },
+        data: {
+          storagePath: undefined,
+          cronSchedule: undefined,
+          retentionCount: undefined,
+        },
+      });
+    });
+  });
+});