fix: import asynccontextmanager for lifespan

app/main.py

@@ -14,6 +14,7 @@ import logging
 from fastapi import FastAPI, Depends, HTTPException, Request
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse
+from contextlib import asynccontextmanager
 
 # ─── Router Imports ───────────────────────────────────────────────────────────
 from app.routers import (