Fix bug

webui/app.py

@@ -184,7 +184,7 @@ runner = ModelRunner(
     forward_thre=0.1,
 )
 
-
+"""
 @app.get("/", response_class=HTMLResponse)
 def index(request: Request):
     task_ids = runner.list_task_ids()
@@ -205,7 +205,10 @@ def index(request: Request):
             "task_items": task_items
         },
     )
-
+"""
+@app.get("/")
+def root():
+    return {"ok": True, "message": "Backend is running. Use POST /api/run and open /docs."}
 
 @app.post("/api/run")
 async def api_run(