refactor: 移除 Dashboard 页面及相关功能，更新路由和组件逻辑

- 移除 Dashboard 相关的组件、特性和测试代码，简化项目结构。
- 更新 PageSkeleton 组件，默认渲染工具页面骨架。
- 修改 RouterContainer 和 RouterProvider 以适应新的默认路由策略，确保用户直接访问 timestamp 页面。
- 更新测试用例，确保在新结构下的功能正常。

src/layout/FeatureNav/useFeatureNav.ts

@@ -0,0 +1,21 @@
+import { useMemo } from 'react';
+import { useRouter } from '@/providers/RouterProvider';
+import type { PageType } from '@/types/storage';
+import { resolveNavFeatures, type NavFeatureItem } from './resolveNavFeatures';
+
+export interface UseFeatureNavReturn {
+  navItems: NavFeatureItem[];
+  currentPage: PageType;
+  navigateTo: (page: PageType) => void;
+}
+
+export function useFeatureNav(): UseFeatureNavReturn {
+  const { currentPage, pageOrder, visiblePages, navigateTo } = useRouter();
+
+  const navItems = useMemo(
+    () => resolveNavFeatures(pageOrder, visiblePages),
+    [pageOrder, visiblePages],
+  );
+
+  return { navItems, currentPage, navigateTo };
+}