update user directory handling to use a fixed temp_output path

app.py

@@ -55,11 +55,13 @@ _trellis_pipeline = None
 
 
 def start_session(req: gr.Request):
-    user_dir = os.path.join(TMP_DIR, str(req.session_hash))
+    user_dir = os.path.join(TMP_DIR, "temp_output")
+    # user_dir = os.path.join(TMP_DIR, str(req.session_hash))
     os.makedirs(user_dir, exist_ok=True)
     
 def end_session(req: gr.Request):
-    user_dir = os.path.join(TMP_DIR, str(req.session_hash))
+    user_dir = os.path.join(TMP_DIR, "temp_output")
+    # user_dir = os.path.join(TMP_DIR, str(req.session_hash))
     shutil.rmtree(user_dir)
 
 def preprocess_image(image: Image.Image) -> Image.Image:
@@ -345,7 +347,8 @@ def image_to_3d(
                 "cfg_strength": slat_guidance_strength,
             },
         )
-
+        temp_dir = os.path.join(TMP_DIR, "temp_output")
+        
         video = render_utils.render_video(outputs['gaussian'][0], num_frames=120)['color']
         video_geo = render_utils.render_video(outputs['mesh'][0], num_frames=120)['normal']
         video = [np.concatenate([video[i], video_geo[i]], axis=1) for i in range(len(video))]