feat(comment): 新增评论屏蔽关系功能

本次提交完整实现了评论屏蔽关系模块，包括：
- 屏蔽关系实体 KeyboardCommentBlockRelation
- 屏蔽请求 DTO CommentBlockReq
- 屏蔽用户 VO CommentBlockedUserVO
- 控制器、服务层及 MyBatis 映射文件

src/main/resources/mapper/KeyboardCommentBlockRelationMapper.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
+<mapper namespace="com.yolo.keyborad.mapper.KeyboardCommentBlockRelationMapper">
+  <resultMap id="BaseResultMap" type="com.yolo.keyborad.model.entity.KeyboardCommentBlockRelation">
+    <!--@mbg.generated-->
+    <!--@Table keyboard_comment_block_relation-->
+    <id column="id" jdbcType="BIGINT" property="id" />
+    <result column="blocker_user_id" jdbcType="BIGINT" property="blockerUserId" />
+    <result column="blocked_user_id" jdbcType="BIGINT" property="blockedUserId" />
+    <result column="scope_type" jdbcType="SMALLINT" property="scopeType" />
+    <result column="scope_id" jdbcType="BIGINT" property="scopeId" />
+    <result column="status" jdbcType="SMALLINT" property="status" />
+    <result column="source" jdbcType="SMALLINT" property="source" />
+    <result column="created_at" jdbcType="TIMESTAMP" property="createdAt" />
+    <result column="updated_at" jdbcType="TIMESTAMP" property="updatedAt" />
+    <result column="deleted_at" jdbcType="TIMESTAMP" property="deletedAt" />
+  </resultMap>
+  <sql id="Base_Column_List">
+    <!--@mbg.generated-->
+    id, blocker_user_id, blocked_user_id, scope_type, scope_id, "status", "source", created_at, 
+    updated_at, deleted_at
+  </sql>
+</mapper>