modify the project, everything go under app folder

app/main.py

@@ -0,0 +1,10 @@
+from fastapi import FastAPI
+from app.auth import router as auth_router
+from app.models import Base
+from app.db import engine
+
+Base.metadata.create_all(bind=engine)
+
+app = FastAPI()
+
+app.include_router(auth_router)