task-6(壳层/路由): 定义后端菜单树到侧边栏节点映射规则并落地

新增 src/layout/menu-mapper.ts：toSidebarEntries 处理分组/顶级路由叶/畸形节点，
groupKeysForActive 按当前路由展开激活分组；AdminLayout 菜单区改用映射结果，
删除旧 visibleChildren/canSee 死逻辑；8 用例覆盖空树/单叶/缺 route 过滤等。

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

@@ -5,7 +5,7 @@ import { ElMessage } from 'element-plus'
 import { useAdminSessionStore } from '@/stores/admin-session'
 import { joinAdminPath } from '@/config/app'
 import { pageTitleOf, topbarUserOf } from '@/layout/topbar-model'
-import type { AdminMenuNode } from '@/types/admin'
+import { groupKeysForActive, toSidebarEntries } from '@/layout/menu-mapper'
 
 const route = useRoute()
 const router = useRouter()
@@ -13,27 +13,12 @@ const session = useAdminSessionStore()
 const collapsed = ref(false)
 
 const activePath = computed(() => route.path)
-const groups = computed(() => session.menuTree.filter((node) => node.children?.length))
+const menuEntries = computed(() => toSidebarEntries(session.menuTree))
+const openedKeys = computed(() => groupKeysForActive(menuEntries.value, route.path))
 const pageTitle = computed(() => pageTitleOf(route.meta.title as string | undefined))
 const userVm = computed(() => topbarUserOf(session.user))
 const logoUrl = joinAdminPath('assets', 'logo.jpg')
 
-function menuPath(node: AdminMenuNode): string {
-  return node.route || '/account/users'
-}
-
-function visibleChildren(node: AdminMenuNode) {
-  return (node.children || []).filter((child) => child.route)
-}
-
-function canSee(node: AdminMenuNode) {
-  return session.isSuperAdmin.valueOf() || hasMenu(node, String(route.meta.menuKey || '')) || node.route === activePath.value
-}
-
-function hasMenu(node: AdminMenuNode, key: string): boolean {
-  return node.key === key || (node.children || []).some((child) => hasMenu(child, key))
-}
-
 async function signOut() {
   try {
     await session.signOut()
@@ -55,23 +40,22 @@ async function signOut() {
       </div>
 
       <el-scrollbar class="admin-menu-scroll">
-        <el-menu :default-active="activePath" :collapse="collapsed" router class="admin-menu">
-          <template v-for="group in groups" :key="group.key">
-            <el-sub-menu :index="group.key">
+        <el-menu :default-active="activePath" :default-openeds="openedKeys" :collapse="collapsed" router class="admin-menu">
+          <template v-for="entry in menuEntries" :key="entry.key">
+            <el-sub-menu v-if="entry.kind === 'group'" :index="entry.key">
               <template #title>
-                <span class="menu-group-title">{{ group.name }}</span>
+                <span class="menu-group-title">{{ entry.name }}</span>
               </template>
-              <el-menu-item
-                v-for="item in visibleChildren(group)"
-                :key="item.key"
-                :index="menuPath(item)"
-              >
+              <el-menu-item v-for="item in entry.children" :key="item.key" :index="item.route">
                 {{ item.name }}
               </el-menu-item>
             </el-sub-menu>
+            <el-menu-item v-else :key="entry.key" :index="entry.route">
+              {{ entry.name }}
+            </el-menu-item>
           </template>
         </el-menu>
-        <el-empty v-if="!groups.length && !session.loading" description="暂无可用菜单" :image-size="72" />
+        <el-empty v-if="!menuEntries.length && !session.loading" description="暂无可用菜单" :image-size="72" />
       </el-scrollbar>
 
       <button class="sidebar-collapse" type="button" @click="collapsed = !collapsed">
@@ -100,5 +84,3 @@ async function signOut() {
     </section>
   </div>
 </template>
-
-