fix: return 201 on backup create

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/server/api/config.py

@@ -126,7 +126,7 @@ def list_backups(
         ) from e
 
 
-@router.post("/backups", response_model=Dict[str, str])
+@router.post("/backups", response_model=Dict[str, str], status_code=status.HTTP_201_CREATED)
 def create_backup(
     name: Optional[str] = None, auth: dict = Depends(require_auth)
 ) -> Dict[str, str]: