add singup endpoint

src/api/dependacies/db_dep.py

@@ -4,10 +4,11 @@ from fastapi import Depends
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from src.core.database import async_session_maker
+from src.utils.db_manager import DBManager
 
 
 async def get_db() -> AsyncGenerator[AsyncSession, None]:
-    async with async_session_maker() as db:
+    async with DBManager(async_session_maker) as db:
         yield db