feat(invite): 新增用户邀请码功能

新增实体、Mapper、Service及Controller接口，支持注册时自动生成与用户查询个人邀请码

src/main/java/com/yolo/keyborad/mapper/KeyboardUserInviteCodesMapper.java

@@ -0,0 +1,12 @@
+package com.yolo.keyborad.mapper;
+
+import com.baomidou.mybatisplus.core.mapper.BaseMapper;
+import com.yolo.keyborad.model.entity.KeyboardUserInviteCodes;
+
+/*
+* @author: ziin
+* @date: 2025/12/18 16:26
+*/
+    
+public interface KeyboardUserInviteCodesMapper extends BaseMapper<KeyboardUserInviteCodes> {
+}