fix: add missing APIRouter import for WebSocket route registration

app/main.py

@@ -6,7 +6,7 @@ import time
 import traceback
 from contextlib import asynccontextmanager
 
-from fastapi import FastAPI, HTTPException, Request, Depends
+from fastapi import FastAPI, HTTPException, Request, Depends, APIRouter
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import FileResponse, JSONResponse
 from fastapi.staticfiles import StaticFiles