fix: create and grant permissions for /app/output to avoid PermissionError

* Added mkdir and chmod for /app/output alongside /app/backend/output
* Ensures Hugging Face Spaces runtime user can write to output folder
* Prevents PermissionError: [Errno 13] Permission denied: '/app/output'

main.py

@@ -27,7 +27,8 @@ app.add_middleware(
     allow_headers=["*"],
 )
 
-UPLOAD_DIR = "temp"
+UPLOAD_DIR = "/tmp/temp"
+
 os.makedirs(UPLOAD_DIR, exist_ok=True)
 # Initialize shared service objects
 try: