refactor: 为 Mapper 接口增加 Mapper 注解，以消除 IDEA 警告标志（减少小白咨询）

实际它并不影响运行，但为了减少麻烦，加上不报警告，那就加上吧

continew-plugin/continew-plugin-open/src/main/java/top/continew/admin/open/mapper/AppMapper.java

@@ -16,6 +16,7 @@
 
 package top.continew.admin.open.mapper;
 
+import org.apache.ibatis.annotations.Mapper;
 import org.apache.ibatis.annotations.Param;
 import org.apache.ibatis.annotations.Select;
 import top.continew.admin.open.model.entity.AppDO;
@@ -28,6 +29,7 @@ import top.continew.starter.security.crypto.annotation.FieldEncrypt;
  * @author chengzi
  * @since 2024/10/17 16:03
  */
+@Mapper
 public interface AppMapper extends BaseMapper<AppDO> {
 
     /**