feat: API key routes, search endpoint, conversation type wiring

- GET/POST/DELETE /api/api-keys blueprint registered
- GET /api/search?q=&content_type=&limit= semantic search endpoint
- create_conversation gains conversation_type param (default "chat")
- cleanup_old_conversations excludes mcp type from retention sweep
- POST /api/chat/conversations accepts conversation_type body field

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/fabledassistant/app.py

@@ -27,6 +27,8 @@ from fabledassistant.routes.groups import groups_bp
 from fabledassistant.routes.shares import shares_bp
 from fabledassistant.routes.in_app_notifications import notifications_bp
 from fabledassistant.routes.users import users_bp
+from fabledassistant.routes.api_keys import api_keys_bp
+from fabledassistant.routes.search import search_bp
 
 STATIC_DIR = Path(__file__).parent / "static"
 logger = logging.getLogger(__name__)
@@ -77,6 +79,8 @@ def create_app() -> Quart:
     app.register_blueprint(shares_bp)
     app.register_blueprint(notifications_bp)
     app.register_blueprint(users_bp)
+    app.register_blueprint(api_keys_bp)
+    app.register_blueprint(search_bp)
 
     @app.before_request
     async def before_request():