fix: 修复默认用户未添加默认角色的bug

src/backend/bisheng/database/models/user.py

@@ -138,6 +138,7 @@ def add_user_and_default_role(cls, user: User) -> User:
             session.refresh(user)
             db_user_role = UserRole(user_id=user.user_id, role_id=DefaultRole)
             session.add(db_user_role)
+            session.commit()
             session.refresh(user)
             return user