fix: correct exact url routing and trailing slash for user preferences api

inventory-backend/app/api/v1/user.py

@@ -12,6 +12,7 @@ user_bp = Blueprint('user', __name__)
 # ==============================================================================
 
 @user_bp.route('/preferences', methods=['GET'])
+@audit_log(module='系统', action='读取偏好配置')
 @jwt_required()
 def get_preferences():
     """
@@ -34,8 +35,8 @@ def get_preferences():
 
 
 @user_bp.route('/preferences', methods=['PUT'])
-@jwt_required()
 @audit_log(module='系统', action='修改偏好配置')
+@jwt_required()
 def save_preferences():
     """
     保存/更新当前用户的 preferences 字段