fix: WecomBind.vue — 修复 auth.user 不存在的问题

auth store 暴露的是独立字段 (name/userId/role) 而非 user 对象，
导致 auth.user?.name 始终为 undefined。

修复:
- auth.name 替代 auth.user?.name
- 调用 /users/me 获取 wecom_userid (store 不存储该字段)
- window.location.href 替代 router.push (企微浏览器兼容)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/views/WecomBind.vue

@@ -11,20 +11,25 @@ const auth = useAuthStore()
 const binding = ref(false)
 const bound = ref(false)
 const errorMsg = ref('')
+const wecomUserId = ref('')
 
 const bindToken = (route.query.token as string) || ''
 
-onMounted(() => {
+onMounted(async () => {
   if (!bindToken) {
     errorMsg.value = '无效的绑定链接'
     setTimeout(() => router.replace('/'), 2000)
     return
   }
   if (!auth.isLoggedIn) {
-    // Not logged in yet — redirect to login (use window.location for WeChat Work browser compat)
     window.location.href = `/login?redirect=${encodeURIComponent(route.fullPath)}`
     return
   }
+  // Fetch current user's wecom_userid
+  try {
+    const res = await api.get('/users/me')
+    wecomUserId.value = res.data.wecom_userid || ''
+  } catch (_) {}
 })
 
 async function doBind() {
@@ -34,7 +39,7 @@ async function doBind() {
     const res = await api.post('/wecom/bind-confirm', { token: bindToken })
     if (res.data.code === 200) {
       bound.value = true
-      auth.user!.wecom_userid = res.data.wecom_userid
+      wecomUserId.value = res.data.wecom_userid
       ElMessage.success('绑定成功！')
       setTimeout(() => router.replace('/'), 1500)
     } else {
@@ -61,23 +66,23 @@ async function doBind() {
       <div class="bind-info">
         <div class="info-row">
           <span class="info-label">当前账号</span>
-          <span class="info-value">{{ auth.user?.name || '--' }}</span>
+          <span class="info-value">{{ auth.name || '--' }}</span>
         </div>
         <div class="info-row">
           <span class="info-label">绑定状态</span>
-          <span :class="['info-tag', auth.user?.wecom_userid ? 'bound' : 'unbound']">
-            {{ auth.user?.wecom_userid ? '已绑定' : '未绑定' }}
+          <span :class="['info-tag', wecomUserId ? 'bound' : 'unbound']">
+            {{ wecomUserId ? '已绑定' : '未绑定' }}
           </span>
         </div>
-        <div v-if="auth.user?.wecom_userid" class="info-row">
+        <div v-if="wecomUserId" class="info-row">
           <span class="info-label">企微ID</span>
-          <span class="info-value">{{ auth.user.wecom_userid }}</span>
+          <span class="info-value">{{ wecomUserId }}</span>
         </div>
       </div>
 
       <div class="bind-actions">
         <el-button
-          v-if="!bound && !auth.user?.wecom_userid"
+          v-if="!bound && !wecomUserId"
           type="primary"
           size="large"
           :loading="binding"