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.ts

@@ -0,0 +1,60 @@
+import { Injectable } from '@nestjs/common';
+import { PrismaService } from '../prisma/prisma.service';
+import { AuditLogService } from '../audit/audit-log.service';
+import { BackupSettings } from '../../generated/prisma';
+import { UpdateBackupSettingsDto } from './dto/update-backup-settings.dto';
+
+const SINGLETON_ID = 'singleton';
+
+function emptyToNull(value: string | undefined): string | null {
+  return value === '' ? null : (value ?? null);
+}
+
+@Injectable()
+export class BackupSettingsService {
+  constructor(
+    private readonly prisma: PrismaService,
+    private readonly auditLog: AuditLogService,
+  ) {}
+
+  async get(): Promise<BackupSettings> {
+    const existing = await this.prisma.backupSettings.findUnique({
+      where: { id: SINGLETON_ID },
+    });
+    if (existing) {
+      return existing;
+    }
+    return this.prisma.backupSettings.create({ data: { id: SINGLETON_ID } });
+  }
+
+  async update(
+    dto: UpdateBackupSettingsDto,
+    actingUserId: string,
+  ): Promise<BackupSettings> {
+    const before = await this.get();
+    const settings = await this.prisma.backupSettings.update({
+      where: { id: SINGLETON_ID },
+      data: {
+        storagePath:
+          dto.storagePath !== undefined
+            ? emptyToNull(dto.storagePath)
+            : undefined,
+        cronSchedule:
+          dto.cronSchedule !== undefined
+            ? emptyToNull(dto.cronSchedule)
+            : undefined,
+        retentionCount:
+          dto.retentionCount !== undefined ? dto.retentionCount : undefined,
+      },
+    });
+    await this.auditLog.record({
+      entityType: 'BackupSettings',
+      entityId: SINGLETON_ID,
+      action: 'UPDATE',
+      userId: actingUserId,
+      beforeData: before,
+      afterData: settings,
+    });
+    return settings;
+  }
+}