feat(T01): auth + user management + RBAC + base frontend + i18n

- Backend: FastAPI, JWT auth (HS256), bcrypt, RBAC middleware
- User CRUD (admin-only), soft-delete, pagination
- Pydantic BaseSettings config, async SQLAlchemy 2.0
- 50 backend tests, 88% coverage
- Frontend: Next.js 14 App Router, Tailwind, design tokens
- Login page, auth context, API client with auto-refresh
- i18n: next-intl, DE/EN (31 keys each)
- 6 base UI components (Button, Input, Card, Table, Modal, Toast)
- 12 frontend tests, npm build success

.a0/next_steps.md

@@ -1,6 +1,8 @@
 # Next Steps
 
-1. User-Freigabe für Phase 3 (Implementation) einholen
-2. Plan-Mode auf implementation_allowed setzen
-3. T01 (Core+Auth) an implementation_engineer delegieren
-4. Danach: T02 (Vehicles+mobile.de)
+1. T02: Vehicle CRUD + List/Filter/Pagination (Backend + Frontend)
+2. Alembic Migration Setup für DB Schema
+3. Docker-Compose für dev/prod erstellen
+4. Redis Integration für Token-Refresh-Storage
+5. Frontend: Dashboard-Page nach Login
+6. Frontend: User Management UI (Admin)