fix: import Header for worker auth

backend/api.py

@@ -11,7 +11,7 @@ from pathlib import Path
 from typing import Any, Dict
 
 from dotenv import load_dotenv
-from fastapi import FastAPI, HTTPException, Response
+from fastapi import FastAPI, HTTPException, Response, Header, Request
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import FileResponse