task-16(壳层/路由): 实现退出登录入口的壳层交互(确认式)

logout.ts 定义 runLogout 纯流程(确认通过才 signOut，异常上抛由壳层反馈)；
AdminLayout 用 ElMessageBox.confirm 确认后再执行 store.signOut($reset + /login)。

admin-frontend-vue/src/layout/AdminLayout.vue

@@ -1,7 +1,7 @@
 <script setup lang="ts">
 import { computed, ref, watch } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
-import { ElMessage } from 'element-plus'
+import { ElMessage, ElMessageBox } from 'element-plus'
 import { useAdminSessionStore } from '@/stores/admin-session'
 import { joinAdminPath } from '@/config/app'
 import { pageTitleOf, topbarUserOf } from '@/layout/topbar-model'
@@ -14,6 +14,13 @@ import {
 import GlobalErrorContainer from '@/layout/GlobalErrorContainer.vue'
 import { initialCollapsed, toggleCollapsed, writeCollapsePreference } from '@/layout/sidebar-collapse'
 import { crumbsForActiveRoute, resolveDocumentTitle, updateDocumentTitle } from '@/layout/title-breadcrumb'
+import {
+  LOGOUT_CONFIRM_CANCEL,
+  LOGOUT_CONFIRM_MESSAGE,
+  LOGOUT_CONFIRM_OK,
+  LOGOUT_CONFIRM_TITLE,
+  runLogout,
+} from '@/layout/logout'
 
 const route = useRoute()
 const router = useRouter()
@@ -52,7 +59,18 @@ watch(
 
 async function signOut() {
   try {
-    await session.signOut()
+    await runLogout({
+      confirm: () =>
+        ElMessageBox.confirm(LOGOUT_CONFIRM_MESSAGE, LOGOUT_CONFIRM_TITLE, {
+          confirmButtonText: LOGOUT_CONFIRM_OK,
+          cancelButtonText: LOGOUT_CONFIRM_CANCEL,
+          type: 'warning',
+        }).then(
+          () => true,
+          () => false,
+        ),
+      signOut: () => session.signOut(),
+    })
   } catch (error) {
     ElMessage.error(error instanceof Error ? error.message : '退出登录失败')
   }