feat: 导航体验优化 — 控制台入口提升 + AppLayout 返回前台链接

BlogLayout 导航菜单新增"控制台"按钮（登录后可见，普通用户→控制台，管理员→管理后台），
移除下拉菜单中冗余的控制台项。AppLayout 侧边栏新增"返回首页"和"AI 助手"入口。
路由调整：根路径指向 AI 助手，/blog 指向博客首页。

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

jog-frontend/src/router/index.js

@@ -19,9 +19,9 @@ const routes = [
     children: [
       {
         path: '',
-        name: 'Home',
-        component: () => import('@/views/Home.vue'),
-        meta: { title: '首页' },
+        name: 'AiAssistant',
+        component: () => import('@/views/AiAssistant.vue'),
+        meta: { title: 'AI 助手' },
       },
       {
         path: 'article/:id',
@@ -30,10 +30,10 @@ const routes = [
         meta: { title: '文章详情' },
       },
       {
-        path: 'ai-assistant',
-        name: 'AiAssistant',
-        component: () => import('@/views/AiAssistant.vue'),
-        meta: { title: 'AI 助手' },
+        path: 'blog',
+        name: 'Blog',
+        component: () => import('@/views/Home.vue'),
+        meta: { title: '博客' },
       },
     ],
   },
@@ -125,7 +125,7 @@ router.beforeEach((to, from, next) => {
   if (to.meta.requiresAuth && !token) {
     next({ name: 'Login', query: { redirect: to.fullPath } })
   } else if (to.meta.requiresAdmin && userInfo?.role !== 'ADMIN') {
-    next({ name: 'Home' })
+    next({ name: 'Blog' })
   } else {
     next()
   }