feat: 新增服务看板页面

实现 Dashboard 看板视图并将应用默认入口由调优改为看板，路由、侧边栏默认菜单与登录跳转同步调整；侧边栏增加导航失败高亮校正，布局与 ECharts 注册柱状图适配看板，补充两份回归脚本、设计走查记录与五张设计截图。

frontend/src/router/index.ts

@@ -11,13 +11,13 @@ const routes: RouteRecordRaw[] = [
   {
     path: '/',
     component: () => import('@/layouts/MainLayout.vue'),
-    redirect: '/fine-tune',
+    redirect: '/dashboard',
     children: [
       // 服务看板
       {
         path: 'dashboard',
         name: 'dashboard',
-        component: () => import('@/components/PlaceholderView.vue'),
+        component: () => import('@/views/dashboard/DashboardView.vue'),
         meta: { title: '服务看板' },
       },
       // 模型调优
@@ -202,7 +202,7 @@ const routes: RouteRecordRaw[] = [
   },
   {
     path: '/:pathMatch(.*)*',
-    redirect: '/fine-tune',
+    redirect: '/dashboard',
   },
 ]
 
@@ -219,7 +219,7 @@ router.beforeEach((to, _from, next) => {
   if (to.meta.public) {
     // 已登录访问登录页则跳转主页
     if (to.name === 'login' && auth.isLoggedIn) {
-      next('/fine-tune')
+      next('/dashboard')
       return
     }
     next()