fix(database): 修复客户表与用户表关联查询的字段映射错误

- 修正了 LEFT JOIN 条件中的字段引用错误
- 将 u.id = a.user_id 更改为 u.user_id = a.user_id
- 确保了用户信息能够正确关联到客户记录上

src/main/java/com/gxwebsoft/credit/mapper/xml/CreditMpCustomerMapper.xml

@@ -6,7 +6,7 @@
     <sql id="selectSql">
         SELECT a.*, u.nickname AS nickname, u.avatar AS avatar, u.phone AS phone
         FROM credit_mp_customer a
-        LEFT JOIN gxwebsoft_core.sys_user u ON u.id = a.user_id
+        LEFT JOIN gxwebsoft_core.sys_user u ON u.user_id = a.user_id
         <where>
             <if test="param.id != null">
                 AND a.id = #{param.id}