fix: proper empty 204 response for jobs/next

backend/api.py

@@ -6,7 +6,7 @@ from pathlib import Path
 from typing import Any, Dict
 
 from dotenv import load_dotenv
-from fastapi import FastAPI, HTTPException
+from fastapi import FastAPI, HTTPException, Response
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import FileResponse
 from backend.sftp_store import SFTPStore
@@ -201,7 +201,7 @@ def jobs_next(x_worker_token: Optional[str] = Header(default=None)):
         if job.status == "queued":
             job.status = "running"
             return asdict(job)
-    return JSONResponse(status_code=204, content=None)
+    return Response(status_code=204)
 
 class StatusReq(BaseModel):
     status: str  # running|done|failed