fix test and add doc

src/server/fastapi_app.py

@@ -31,6 +31,7 @@ from src.server.controllers.error_controller import (
 from src.server.controllers.health_controller import router as health_router
 from src.server.controllers.page_controller import router as page_router
 from src.server.middleware.auth import AuthMiddleware
+from src.server.middleware.error_handler import register_exception_handlers
 from src.server.services.progress_service import get_progress_service
 from src.server.services.websocket_service import get_websocket_service
 
@@ -68,6 +69,9 @@ app.include_router(anime_router)
 app.include_router(download_router)
 app.include_router(websocket_router)
 
+# Register exception handlers
+register_exception_handlers(app)
+
 # Global variables for application state
 series_app: Optional[SeriesApp] = None