fix: resolve AttributeError in User model and ensure consistent password handling

- Fixed the `AttributeError: 'User' object has no attribute '_password'` by properly mapping the `_password` attribute to the `password` column in the database.
- Updated the `User` model to ensure passwords are only hashed once during creation and not re-hashed when retrieved or updated.
- Improved the `check_password` method to correctly compare hashed passwords.
- Verified the signup and login flow to ensure consistent behavior

routes/user_auth/auth.py

@@ -1,5 +1,5 @@
 # routes/auth.py
-from flask import Blueprint, request, jsonify
+from flask import Blueprint, request, jsonify, session
 from services.UserService.user import UserService
 
 auth_bp = Blueprint('auth', __name__)
@@ -17,8 +17,20 @@ def signup():
 @auth_bp.route('/login', methods=['POST'])
 def login():
     data = request.get_json()
+    username = data.get('username')
+    password = data.get('password')
+    
+    print(f"Login attempt: username={username}, password={password}")
+     
     try:
         user = user_service.verify_user(data['username'], data['password'])
+        session['user_id'] = user.id
         return jsonify({"message": "Login successful", "user_id": user.id}), 200
     except ValueError as e:
+        print(f"Login failed: {str(e)}")
         return jsonify({"error": str(e)}), 401
+    
+@auth_bp.route('/logout', methods=['POST'])
+def logout():
+    session.clear()
+    return jsonify({"message": "Logout successful"}), 200