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/scripts/regression-default-dashboard.mjs

@@ -0,0 +1,39 @@
+import { readFileSync } from 'node:fs'
+import { resolve } from 'node:path'
+import { fileURLToPath } from 'node:url'
+
+const root = resolve(fileURLToPath(new URL('..', import.meta.url)))
+
+function read(relativePath) {
+  return readFileSync(resolve(root, relativePath), 'utf8')
+}
+
+function assert(condition, message) {
+  if (!condition) throw new Error(message)
+}
+
+const router = read('src/router/index.ts')
+const login = read('src/views/login/LoginView.vue')
+const sidebar = read('src/components/AppSidebar.vue')
+
+assert(
+  router.includes("redirect: '/dashboard'"),
+  'The authenticated root and fallback routes should default to 服务看板',
+)
+
+assert(
+  router.includes("next('/dashboard')"),
+  'An authenticated user visiting the login page should enter 服务看板',
+)
+
+assert(
+  login.includes("router.push('/dashboard')"),
+  'A successful login should navigate to 服务看板',
+)
+
+assert(
+  sidebar.includes("route.path.split('/')[1] || 'dashboard'"),
+  'The sidebar fallback active item should be 服务看板',
+)
+
+console.log('default-dashboard regression checks passed')