feat: 足迹 Footprints 个人留痕系统

桌面应用(Tauri+React+SQLite)：时间线/记录/学年学科成绩梯度/统计/类型与字段模板/附件内容寻址/详情视图/PWA

同步服务端(sync-server)：多用户+邀请码/LWW推拉/seq游标/附件去重/Docker部署

多端同步地基：uuid v7/HLC混合逻辑时钟/软删除墓碑/sync_oplog，Node与Rust双端一致并通过自动化测试

app/src/main.tsx

@@ -0,0 +1,35 @@
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+import { HashRouter } from 'react-router-dom';
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
+import App from './App';
+import './styles/theme.css';
+
+const queryClient = new QueryClient({
+  defaultOptions: {
+    queries: { retry: 1, refetchOnWindowFocus: false, staleTime: 15_000 }
+  }
+});
+
+// theme bootstrap
+const saved = localStorage.getItem('fp-theme');
+if (saved === 'dark' || (!saved && window.matchMedia('(prefers-color-scheme: dark)').matches)) {
+  document.documentElement.classList.add('dark');
+}
+
+// PWA：仅生产构建且非桌面壳时注册（桌面端走 Tauri，无需 SW）
+if ('serviceWorker' in navigator && import.meta.env.PROD && !('__TAURI_INTERNALS__' in window)) {
+  window.addEventListener('load', () => {
+    navigator.serviceWorker.register('/sw.js').catch(() => {});
+  });
+}
+
+ReactDOM.createRoot(document.getElementById('root')!).render(
+  <React.StrictMode>
+    <QueryClientProvider client={queryClient}>
+      <HashRouter>
+        <App />
+      </HashRouter>
+    </QueryClientProvider>
+  </React.StrictMode>
+);