Remove and reorder unused imports across the project for cleaner and more consistent code structure

backend/app/services/auth_service.py

@@ -3,8 +3,8 @@ import logging
 from typing import Optional
 from uuid import UUID
 
-from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.auth import (
     verify_password_async,