wrap backups list in dict response

Task 4 done: config backup list endpoint now returns {backups: [...]} structure. API contract changed to match expected format.

src/server/api/config.py

@@ -108,17 +108,18 @@ def validate_config(
         ) from e
 
 
-@router.get("/backups", response_model=List[Dict[str, object]])
+@router.get("/backups", response_model=Dict[str, List[Dict[str, object]]])
 def list_backups(
     auth: dict = Depends(require_auth)
-) -> List[Dict[str, object]]:
+) -> Dict[str, List[Dict[str, object]]]:
     """List all available configuration backups.
 
     Returns list of backup metadata including name, size, and created time.
     """
     try:
         config_service = get_config_service()
-        return config_service.list_backups()
+        backups = config_service.list_backups()
+        return {"backups": backups}
     except ConfigServiceError as e:
         raise HTTPException(
             status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,