refactor(整合): 将更新日志改为模态框实现并补充最近20条更新记录

- 将 ChangelogPage 改为 ChangelogModal 模态框组件
- 移除 /changelog 和 /updates 路由，改为模态框弹出
- 修改 Header 按钮点击行为，触发模态框而非路由跳转
- 根据最近20条 git 提交记录补充更新数据
- 优化模态框样式，支持响应式布局和深色模式
- 修复 JSON 中的引号转义问题

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <noreply@hapi.run>

src/App.tsx

@@ -1,4 +1,4 @@
-import { Routes, Route, Navigate } from 'react-router-dom'
+import { Routes, Route } from 'react-router-dom'
 import { Layout } from './components/layout/Layout'
 import { HomePage } from './pages/HomePage'
 import { KnowledgeAreasPage } from './pages/KnowledgeAreasPage'
@@ -8,7 +8,6 @@ import { ProcessMatrixPage } from './pages/ProcessMatrixPage'
 import { ProcessGraphPage } from './pages/ProcessGraphPage'
 import { ArtifactDetailPage } from './pages/ArtifactDetailPage'
 import { ToolDetailPage } from './pages/ToolDetailPage'
-import { ChangelogPage } from './pages/ChangelogPage'
 import { SettingsPage } from './pages/SettingsPage'
 import ProcessPracticePage from './pages/ProcessPracticePage'
 
@@ -27,8 +26,6 @@ function App() {
         <Route path="/process-practice" element={<ProcessPracticePage />} />
         <Route path="/artifact/:id" element={<ArtifactDetailPage />} />
         <Route path="/tool/:id" element={<ToolDetailPage />} />
-        <Route path="/changelog" element={<ChangelogPage />} />
-        <Route path="/updates" element={<Navigate to="/changelog" replace />} />
         <Route path="/settings" element={<SettingsPage />} />
       </Routes>
     </Layout>