Show Feishu app visibility and preserve sync toggle

frontend/src/locales/en-US.json

@@ -794,7 +794,7 @@
     "commonSetupTitle": "First-time shared network setup", "commonSetupHint": "Check permissions, default route and IPv4 forwarding. Enable shared forwarding only when needed; install protocol-specific dependencies separately in Create Tunnel.", "hostRoot": "Privileges", "hostRoute": "Default route", "hostForward": "IPv4 forwarding", "enableForwarding": "Enable IPv4 forwarding", "forwardingEnabled": "IPv4 forwarding enabled"
   },
   "feishuSync": {
-    "title": "Feishu directory", "hint": "Import manually or every 30 minutes when enabled. Imported members do not receive VPN access or tunnel grants. Names are shown exactly as returned by Feishu.", "permissions": "Grant app identity access to department and user lists, publish the app, and set its directory visibility to the intended departments and members.", "auto": "Auto sync (30 min)", "run": "Sync now", "lastSuccess": "Last success", "counts": "Departments {departments} · members {members}", "name": "Name", "departments": "Department IDs", "firstMembers": "Showing the first 500 members", "saved": "Sync settings saved", "started": "Sync started; watch progress below", "done": "Directory sync complete", "failed": "Directory sync failed"
+    "title": "Feishu directory", "hint": "Import manually or every 30 minutes when enabled. Imported members do not receive VPN access or tunnel grants. Names are shown exactly as returned by Feishu.", "permissions": "Grant app identity access to department and user lists, publish the app, and set its directory visibility to the intended departments and members.", "auto": "Auto sync (30 min)", "run": "Sync now", "lastSuccess": "Last success", "counts": "Departments {departments} · members {members}", "visibility": "App-visible scope: {departments} department roots · {users} individually visible users (not the enterprise total)", "noDepartments": "Only individually visible members were returned. Grant department read access and expand the app's directory visibility in Feishu, publish, then sync again.", "name": "Name", "departments": "Department IDs", "firstMembers": "Showing the first 500 members", "saved": "Sync settings saved", "started": "Sync started; watch progress below", "done": "Directory sync complete", "failed": "Directory sync failed"
   },
   "feishuDirectory": {
     "title": "Feishu directory lookup",

frontend/src/locales/zh-CN.json

@@ -794,7 +794,7 @@
     "commonSetupTitle": "首次引导 · 通用网络环境", "commonSetupHint": "检查服务权限、默认出口和 IPv4 转发。仅按需开启通用转发；各专线协议的依赖在“创建专线”中分别安装。", "hostRoot": "运行权限", "hostRoute": "默认出口", "hostForward": "IPv4 转发", "enableForwarding": "开启 IPv4 转发", "forwardingEnabled": "IPv4 转发已开启"
   },
   "feishuSync": {
-    "title": "飞书组织与成员", "hint": "手动导入，或开启后每 30 分钟同步一次。导入不会自动开通 VPN 或授予专线权限；仅显示飞书返回的姓名。", "permissions": "需应用身份读取部门及直属成员（如 contact:department.base:readonly、contact:user.department:readonly）；发布应用，并设置通讯录可见范围。具体权限以飞书接口报错为准。", "auto": "自动同步（30 分钟）", "run": "立即同步", "lastSuccess": "上次成功", "counts": "部门 {departments} · 成员 {members}", "name": "姓名", "departments": "部门 ID", "firstMembers": "仅显示前 500 位成员", "saved": "同步设置已保存", "started": "已开始同步，可查看下方进度", "done": "通讯录同步完成", "failed": "通讯录同步失败"
+    "title": "飞书组织与成员", "hint": "手动导入，或开启后每 30 分钟同步一次。导入不会自动开通 VPN 或授予专线权限；仅显示飞书返回的姓名。", "permissions": "需应用身份读取部门及直属成员（如 contact:department.base:readonly、contact:user.department:readonly）；发布应用，并设置通讯录可见范围。具体权限以飞书接口报错为准。", "auto": "自动同步（30 分钟）", "run": "立即同步", "lastSuccess": "上次成功", "counts": "部门 {departments} · 成员 {members}", "visibility": "飞书应用当前可见范围：部门入口 {departments} · 单独成员 {users}（与企业通讯录总人数不同）", "noDepartments": "当前只读到单独授权的成员，没有可见部门。请在飞书配置应用的部门读取权限和通讯录可见范围，发布后重新同步。", "name": "姓名", "departments": "部门 ID", "firstMembers": "仅显示前 500 位成员", "saved": "同步设置已保存", "started": "已开始同步，可查看下方进度", "done": "通讯录同步完成", "failed": "通讯录同步失败"
   },
   "feishuDirectory": {
     "title": "飞书姓名查询",

frontend/src/views/settings/components/IdentitySettings.vue

@@ -66,6 +66,8 @@
         <el-button :loading="syncLoading" @click="loadSync">{{ $t('tls.refresh') }}</el-button>
       </div>
       <p class="tls-hint">{{ $t('feishuSync.lastSuccess') }}：{{ syncStatus.last_success ? new Date(syncStatus.last_success).toLocaleString() : '—' }} · {{ $t('feishuSync.counts', { departments: syncStatus.departments || 0, members: syncStatus.members || 0 }) }}</p>
+      <p v-if="syncStatus.last_success" class="tls-hint">{{ $t('feishuSync.visibility', { departments: syncStatus.visible_departments || 0, users: syncStatus.visible_users || 0 }) }}</p>
+      <el-alert v-if="syncStatus.last_success && !syncStatus.departments" type="warning" :closable="false" :title="$t('feishuSync.noDepartments')" style="margin-bottom:12px" />
       <el-alert v-if="syncStatus.last_error || syncError" type="warning" :closable="false" :title="syncError || syncStatus.last_error" style="margin-bottom:12px" />
       <el-tree v-if="syncDepartments.length" :data="syncDepartmentTree" node-key="id" :props="{ label: 'name', children: 'children' }" style="margin:12px 0;max-height:260px;overflow:auto" />
       <el-table :data="syncMembers" size="small" max-height="340" v-loading="syncLoading">