feat(dsgvo): Löschkonzept/Aufbewahrungsfristen (Auto-Purge)

Neuer retention_service.py: Lohn-/zeitrelevante Daten (time_entries,
hours_payouts) werden nach konfigurierbarer Frist gelöscht
(company.settings.retention_lohn_years, Default 10 Jahre). Technische
Tabellen mit fester Frist: audit_logs (3 Jahre), abgelaufene
sessions/password_resets (sofort).

Täglicher Scheduler-Job (03:00 Uhr, Redis-Tageslock analog Reminder-Jobs)
plus manuelle Trigger: POST /companies/me/run-retention-purge
(COMPANY_ADMIN/HR, nur eigene Firma) und POST /admin/run-retention-purge
(SUPER_ADMIN, global inkl. technischer Tabellen).

Letzter offener Punkt aus dem DSGVO-Löschkonzept (Art. 15/17 bereits erledigt).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gis16MnuwkYcivLrSxK1pD

backend/app/services/scheduler_service.py

@@ -23,6 +23,7 @@ from app.models.user import User, UserRole
 from app.models.vacation_balance import VacationBalance
 from app.services.absence_service import absence_service
 from app.services.email_service import email_service
+from app.services.retention_service import run_retention_purge
 
 log = logging.getLogger(__name__)
 
@@ -188,6 +189,22 @@ async def _run_job(name: str, fn) -> None:
         log.exception("Reminder-Job %s fehlgeschlagen: %s", name, exc)
 
 
+async def _run_purge_job(name: str, fn) -> None:
+    if not _acquire_daily_lock(name):
+        log.info("Purge-Job %s bereits von anderem Prozess übernommen.", name)
+        return
+    from sqlalchemy import text
+    from app.core.database import AsyncSessionLocal
+    try:
+        async with AsyncSessionLocal() as db:
+            await db.execute(text("SET LOCAL app.bypass_rls = 'on'"))
+            result = await fn(db)
+            await db.commit()
+        log.info("Purge-Job %s: %s", name, result)
+    except Exception as exc:
+        log.exception("Purge-Job %s fehlgeschlagen: %s", name, exc)
+
+
 def start() -> None:
     global _scheduler
     if _scheduler is not None:
@@ -207,6 +224,8 @@ def start() -> None:
                        args=["carryover_expiry", run_carryover_expiry], id="carryover_expiry")
     _scheduler.add_job(_run_job, CronTrigger(hour=hour, minute=20),
                        args=["certificate_overdue", run_certificate_overdue], id="certificate_overdue")
+    _scheduler.add_job(_run_purge_job, CronTrigger(hour=3, minute=0),
+                       args=["retention_purge", run_retention_purge], id="retention_purge")
     _scheduler.start()
     log.info("Reminder-Scheduler gestartet (täglich ab %02d:00 Uhr).", hour)