AI Vision: multi-provider config, model testing, per-client AI preferences

Backend:
- Add ai_provider + ai_model columns to APIClient model
- New admin_ai router: GET /admin/api/ai/status + POST /admin/api/ai/test
- Update ai_vision.py: provider_override + model_override support
- Update pipeline: load client AI prefs for image processing
- ClientUpdate/ClientResponse schemas include ai_provider/ai_model

Frontend:
- New AIConfigSection component: provider list, model dropdowns,
  test button with live results (no page refresh needed)
- AI types (ai.types.ts) + API (api/ai.ts)
- APIClient types extended with ai_provider/ai_model

app/main.py

@@ -12,7 +12,7 @@ from slowapi.errors import RateLimitExceeded
 from app.config import settings
 from app.database import init_db
 from app.logging_config import configure_logging
-from app.routers import images_router, ai_router, auth_router, files_router, ws_router, admin_router
+from app.routers import images_router, ai_router, auth_router, files_router, ws_router, admin_router, admin_ai_router
 from app.middleware import limiter
 from app.middleware.logging_middleware import LoggingMiddleware
 from app.middleware.versioning import APIVersioningMiddleware
@@ -171,6 +171,7 @@ app.include_router(api_v1_router)
 # ── Routers non-versionnés ──────────────────────────────────
 app.include_router(ws_router)
 app.include_router(admin_router)
+app.include_router(admin_ai_router)
 
 
 # ── Routes utilitaires ──────────────────────────────────────