feat: platform backbone and field capture complete (checkpoint)

Platform backbone (plan 2026-10-13-plattform-rueckgrat), all tasks reviewed:
- webhooks with delivery table, retries and stable delivery id
- calendar handlers; a finished task removes its Outlook event
- tasks, automations, inspections, varroa, treatments, feedings,
  harvests, colonies, wintering, stock and bottling record domain events
  in the same transaction; legacy post-commit calls removed
- row locks through one helper (lockRowForUpdate, lockRowsForShare,
  lockRowsForUpdate)
- job framework with JobRun, cli exit codes, cleanup, task templates,
  daily evaluation, hourly app-backup and the rekey job
- system API and page "Verwaltung > System" with retry
- @nestjs/schedule removed, guard tests against in-process schedulers

Field capture T3 (plan 2026-10-13-t3-erfassung-am-stand), all tasks reviewed:
- inspection photo offline without metadata
- bulk capture for treatments, feedings and varroa (backend + frontend)
- offline stand mode with service worker, offline pages and packs
- offline session, cold start and logout on shared devices

Docs: ARCHITECTURE.md assumptions and sections updated, TASKS.md.
Gates: backend lint, typecheck, 1770 unit, 420 e2e, build, no schema
drift; frontend lint, typecheck, 913 tests, build. Not rolled out.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

ApiCore-Backend/src/backup/backup-due.spec.ts

@@ -0,0 +1,82 @@
+import { runInNewContext } from 'node:vm';
+import { BACKUP_SCHEDULE_TIME_ZONE, isBackupDue } from './backup-due';
+
+describe('isBackupDue', () => {
+  it('reads the schedule in Europe/Berlin by default', () => {
+    expect(BACKUP_SCHEDULE_TIME_ZONE).toBe('Europe/Berlin');
+  });
+
+  it('is due when there is no backup yet', () => {
+    expect(
+      isBackupDue('0 3 * * *', null, new Date('2026-10-13T00:30:00Z')),
+    ).toBe(true);
+  });
+
+  it('is not due again on the same day for "0 3 * * *"', () =>
+    expect(
+      isBackupDue(
+        '0 3 * * *',
+        new Date('2026-10-12T01:00:00Z'),
+        new Date('2026-10-13T00:30:00Z'),
+      ),
+    ).toBe(false));
+
+  it('is due after the next 03:00 Europe/Berlin', () =>
+    expect(
+      isBackupDue(
+        '0 3 * * *',
+        new Date('2026-10-12T01:00:00Z'),
+        new Date('2026-10-13T01:05:00Z'),
+      ),
+    ).toBe(true));
+
+  it('is due exactly at the next scheduled time', () =>
+    expect(
+      isBackupDue(
+        '0 3 * * *',
+        new Date('2026-10-12T01:00:00Z'),
+        new Date('2026-10-13T01:00:00Z'),
+      ),
+    ).toBe(true));
+
+  it('counts a backup written after the scheduled time (e.g. "Jetzt sichern") as covering it', () =>
+    expect(
+      isBackupDue(
+        '0 3 * * *',
+        new Date('2026-10-13T01:10:00Z'),
+        new Date('2026-10-13T02:00:00Z'),
+      ),
+    ).toBe(false));
+
+  it('stays due after a missed run until a backup exists', () =>
+    expect(
+      isBackupDue(
+        '0 3 * * *',
+        new Date('2026-10-10T01:00:00Z'),
+        new Date('2026-10-13T05:00:00Z'),
+      ),
+    ).toBe(true));
+
+  it('uses the given time zone', () => {
+    const lastBackupAt = new Date('2026-10-12T03:00:00Z');
+    const now = new Date('2026-10-13T02:00:00Z');
+
+    // Next 03:00 UTC is 03:00Z, next 03:00 Berlin was 01:00Z.
+    expect(isBackupDue('0 3 * * *', lastBackupAt, now, 'UTC')).toBe(false);
+    expect(isBackupDue('0 3 * * *', lastBackupAt, now)).toBe(true);
+  });
+
+  // fs.Stats.mtime is created by Node's core; under Jest it is not an
+  // instance of the test's Date (cron checks `instanceof Date`).
+  it('accepts a Date from another realm', () => {
+    const foreign = runInNewContext('new Date("2026-10-12T01:00:00Z")') as Date;
+
+    expect(
+      isBackupDue('0 3 * * *', foreign, new Date('2026-10-13T00:30:00Z')),
+    ).toBe(false);
+  });
+
+  it('rejects an invalid schedule even without a backup', () => {
+    expect(() => isBackupDue('every night', null, new Date())).toThrow();
+  });
+});