fix: remove unused Response import, constrain format param to Literal[json,zip]

backend/app/api/configs.py

@@ -1,5 +1,5 @@
-from typing import Optional
-from fastapi import APIRouter, Depends, HTTPException, Response
+from typing import Literal, Optional
+from fastapi import APIRouter, Depends, HTTPException
 from fastapi.responses import StreamingResponse
 from sqlalchemy.orm import Session, selectinload
 from app import models, schemas
@@ -81,7 +81,7 @@ def delete_config(
 @router.post("/{config_id}/generate")
 def generate_config(
     config_id: int,
-    format: str = "json",
+    format: Literal["json", "zip"] = "json",
     body: Optional[schemas.GenerateRequest] = None,
     db: Session = Depends(get_db),
     current_user: Optional[models.User] = Depends(get_optional_user),