feat(db): add sys_user service-account WeChat bind columns

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/models/models.py

@@ -32,6 +32,9 @@ class SysUser(Base):
     email = Column(String(50), nullable=False, default="", comment="用户邮箱")
     phone_no = Column(String(11), nullable=False, default="", comment="手机号码")
     wx_openid = Column(String(64), nullable=True, comment="微信小程序 openid")
+    wx_mp_openid = Column(String(64), nullable=True, comment="微信服务号 openid")
+    wx_unionid = Column(String(64), nullable=True, comment="微信开放平台 unionid")
+    wx_mp_bind_time = Column(DateTime, nullable=True, comment="服务号绑定时间")
     hire_date = Column(Date, nullable=True, comment="入职日期")
     probation_months = Column(Integer, nullable=True, comment="试用期月数")
     last_work_day = Column(Date, nullable=True, comment="最后工作日")

docs/sql/alter-sys-user-wx-mp-openid.sql

@@ -0,0 +1,13 @@
+-- 员工微信服务号 openid / unionid 绑定字段（OA 审批通知）
+-- MySQL 5.7：唯一索引允许多个 NULL
+
+ALTER TABLE `sys_user`
+  ADD COLUMN `wx_mp_openid` varchar(64) DEFAULT NULL COMMENT '微信服务号 openid' AFTER `wx_openid`,
+  ADD COLUMN `wx_unionid` varchar(64) DEFAULT NULL COMMENT '微信开放平台 unionid' AFTER `wx_mp_openid`,
+  ADD COLUMN `wx_mp_bind_time` datetime DEFAULT NULL COMMENT '服务号绑定时间' AFTER `wx_unionid`;
+
+ALTER TABLE `sys_user`
+  ADD UNIQUE INDEX `uk_sys_user_wx_mp_openid` (`wx_mp_openid`);
+
+ALTER TABLE `sys_user`
+  ADD INDEX `idx_sys_user_wx_unionid` (`wx_unionid`);