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/resolveNavFeatures.ts

@@ -0,0 +1,27 @@
+import { getFeatureByKey, type FeatureConfig } from '@/config/features';
+import type { PageType } from '@/types/storage';
+
+export interface NavFeatureItem {
+  key: PageType;
+  feature: FeatureConfig & { icon: NonNullable<FeatureConfig['icon']> };
+}
+
+function isNavFeature(feature: FeatureConfig): feature is NavFeatureItem['feature'] {
+  return feature.icon != null;
+}
+
+export function resolveNavFeatures(keys: PageType[], visiblePages: PageType[]): NavFeatureItem[] {
+  const visibleSet = new Set(visiblePages);
+  const items: NavFeatureItem[] = [];
+
+  for (const key of keys) {
+    if (!visibleSet.has(key)) continue;
+
+    const feature = getFeatureByKey(key);
+    if (!feature || !isNavFeature(feature)) continue;
+
+    items.push({ key, feature });
+  }
+
+  return items;
+}