perf(前端): 优化页面加载性能和用户体验

- 添加路由预加载功能，使用 requestIdleCallback 在浏览器空闲时预加载
- 配置 Vite manualChunks 分离 vendor 库（vue/ui/chart/i18n/misc）
- 新增 NavigationProgress 导航进度条组件，支持防闪烁和无障碍
- 集成 Vitest 测试框架，添加 40 个单元测试和集成测试
- 支持 prefers-reduced-motion 和暗色模式

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

frontend/src/__tests__/setup.ts

@@ -0,0 +1,45 @@
+/**
+ * Vitest 测试环境设置
+ * 提供全局 mock 和测试工具
+ */
+import { config } from '@vue/test-utils'
+import { vi } from 'vitest'
+
+// Mock requestIdleCallback (Safari < 15 不支持)
+if (typeof globalThis.requestIdleCallback === 'undefined') {
+  globalThis.requestIdleCallback = ((callback: IdleRequestCallback) => {
+    return window.setTimeout(() => callback({ didTimeout: false, timeRemaining: () => 50 }), 1)
+  }) as unknown as typeof requestIdleCallback
+}
+
+if (typeof globalThis.cancelIdleCallback === 'undefined') {
+  globalThis.cancelIdleCallback = ((id: number) => {
+    window.clearTimeout(id)
+  }) as unknown as typeof cancelIdleCallback
+}
+
+// Mock IntersectionObserver
+class MockIntersectionObserver {
+  observe = vi.fn()
+  disconnect = vi.fn()
+  unobserve = vi.fn()
+}
+
+globalThis.IntersectionObserver = MockIntersectionObserver as unknown as typeof IntersectionObserver
+
+// Mock ResizeObserver
+class MockResizeObserver {
+  observe = vi.fn()
+  disconnect = vi.fn()
+  unobserve = vi.fn()
+}
+
+globalThis.ResizeObserver = MockResizeObserver as unknown as typeof ResizeObserver
+
+// Vue Test Utils 全局配置
+config.global.stubs = {
+  // 可以在这里添加全局 stub
+}
+
+// 设置全局测试超时
+vi.setConfig({ testTimeout: 10000 })