数据库变更：更新BuyMapper中的数据库引用

将`BuyMapper.xml`中的数据库引用从`groups`更新为`three-groups`，确保正确映射数据库连接日志的插入操作。

src/main/resources/mapper/system/BuyMapper.xml

@@ -11,7 +11,7 @@
     </insert>
 
     <insert id="insertPurchaseRecord">
-        INSERT INTO `groups`.`connect_log` ( `data_name`, `amount`, `create_time`)
+        INSERT INTO `three-groups`.`connect_log` ( `data_name`, `amount`, `create_time`)
         VALUES (#{dataName}, #{amount}, new());
     </insert>