refactor(system): 优化代码结构和查询效率

- 移除了 RoleMenuRepository 中的冗余方法 selectByRoleId
- 优化了 UserServiceImpl 中的权限刷新逻辑，减少了数据库查询次数

src/main/java/com/zsc/edu/gateway/modules/system/repo/RoleMenuRepository.java

@@ -11,6 +11,4 @@ import java.util.Set;
  * @author Yao
  */
 public interface RoleMenuRepository extends BaseMapper<RoleMenu> {
-    @Select("select * from role_menu where role_id = #{roleId}")
-    Set<RoleMenu> selectByRoleId(@Param("roleId") Long roleId);
 }

src/main/java/com/zsc/edu/gateway/modules/system/service/impl/UserServiceImpl.java

@@ -140,9 +140,9 @@ public class UserServiceImpl extends ServiceImpl<UserRepository, User> implement
                 .update();
         userDetails.setRole(role);
         if (updated) {
-            // 刷新权限表
-            List<Menu> menus = menuRepository.selectByRoleId(roleId);
-            Set<String> permissions = menus.stream().map(Menu::getPermissions).collect(Collectors.toSet());
+            Set<String> permissions = menuRepository.selectByRoleId(roleId).stream()
+                    .map(Menu::getPermissions)
+                    .collect(Collectors.toSet());
             userDetails.setPermissions(permissions);
             SecurityUtil.setUserInfo(userDetails);
         }