fix(menu): change parentId validation from integer to string

apps/box-mgnt-api/src/mgnt-backend/core/menu/menu.dto.ts

@@ -19,7 +19,7 @@ export class MenuDto {
     description: '父菜单 ID，若为顶级菜单则为空',
     example: 0,
   })
-  @IsInt()
+  @IsString()
   @IsOptional()
   parentId?: string;