feat: add validation for minimum length on various fields and update type definitions

backend/app/main.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from collections.abc import AsyncIterator
 from contextlib import asynccontextmanager
 
 from fastapi import APIRouter, FastAPI
@@ -26,8 +27,8 @@ configure_logging()
 
 
 @asynccontextmanager
-async def lifespan(_: FastAPI):
-    init_db()
+async def lifespan(_: FastAPI) -> AsyncIterator[None]:
+    await init_db()
     yield