refactor: 优化组件并添加测试覆盖

- 创建 CLAUDE.md 项目开发指导文档
- 提取公共常量到 components/constants.ts
- 修复 TimestampToDatetime 重复插件扩展问题
- 修复 DatetimeToTimestamp 时区解析问题
- 优化 RoutePersistence 移除不必要依赖
- 添加 Vitest 测试框架配置
- 为所有组件编写单元测试 (16个测试用例)
- 更新 .gitignore 忽略测试结果目录

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/__tests__/TimestampToDatetime.test.tsx

@@ -0,0 +1,17 @@
+import { render, screen } from '@testing-library/react';
+import { TimestampToDatetime } from '../TimestampToDatetime';
+
+describe('TimestampToDatetime', () => {
+  it('应该正确渲染组件', () => {
+    render(<TimestampToDatetime />);
+    expect(screen.getByLabelText('输入时间戳')).toBeInTheDocument();
+    expect(screen.getByText('转换')).toBeInTheDocument();
+    expect(screen.getByLabelText('转换结果')).toBeInTheDocument();
+  });
+
+  it('应该初始化为当前时间戳', () => {
+    render(<TimestampToDatetime />);
+    const input = screen.getByLabelText('输入时间戳') as HTMLInputElement;
+    expect(input.value).toMatch(/^\d{13}$/);
+  });
+});