Update app.py

app.py

@@ -3,6 +3,7 @@ from fastapi import FastAPI, Depends, HTTPException, BackgroundTasks
 from fastapi.middleware.cors import CORSMiddleware
 import gradio as gr
 from services.chat_service import ChatService
+from services.model_service import ModelService
 from services.data_service import DataService
 from services.faq_service import FAQService
 from auth.auth_handler import get_api_key