file rename fix

backend/youtube.py

@@ -6,6 +6,7 @@ Downloads extract audio as MP3 using ffmpeg post-processing.
 
 import asyncio
 import re
+import shutil
 import uuid
 from pathlib import Path
 from typing import Any
@@ -154,7 +155,7 @@ async def _run_download(
         _jobs[job_id]["error"] = "Converted file not found — is ffmpeg installed?"
         return
 
-    temp_mp3.rename(final_path)
+    shutil.move(str(temp_mp3), str(final_path))
 
     # Write ID3 tags + embed album art
     _jobs[job_id]["status"] = "tagging"