feat(K): Phase K EU Compliance — AI Registry, DPIA, Incident Register, Retention Admin, Tests, Doku

- K-REG: GET /api/v1/compliance/ai-registry — lists all agents with ai_use_case_metadata
- K-DPIA: GET /api/v1/compliance/dpia-template — pre-filled DPIA template export
- K-INC: ComplianceIncident model, Migration 0133 (RLS), CRUD routes (admin-only)
- K-RET: GET/PATCH /api/v1/compliance/retention-policies — 5 policies editable
- K-COMP-TEST: 12/12 integration tests pass
- K-DOC: docs/compliance.md — Betriebsdoku
- Frontend: ComplianceTab.tsx in SettingsAI.tsx (new tab)
- 13 files created/modified

app/models/system_settings.py

@@ -54,3 +54,5 @@ class SystemSettings(Base, TenantMixin):
     backup_enabled: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False, server_default="false")
     # Automation plugin settings (JSONB)
     automation_config: Mapped[dict | None] = mapped_column(JSONB, nullable=True)
+    # Retention policy overrides (JSONB) — compliance module
+    retention_config: Mapped[dict | None] = mapped_column(JSONB, nullable=True)