feat: Vike 骨架（pages feed+spa / renderer 双端入口 / AppShell 拆分 / serverClient）

vite.config 接入 vike 插件并改产出 dist/client+dist/server；feed 白名单 route 匹配 /、/board/:id、/post/:id(.html)；spa catch-all ssr:false；onRenderHtml renderToReadableStream 等 allReady 输出完整 HTML 并带主题/缩放脚本；onRenderClient 沿用样式表等待+冷启动预热+hydrate 回退；getHomeStoreState 作用域 + hydrating 变体入 RequestScope；删除 index.html 与 main.tsx

frontend/src/AppShell.tsx

@@ -0,0 +1,24 @@
+import type { ReactNode } from 'react';
+import './styles/global.css';
+import { AuthProvider } from './hooks/useAuth';
+import { ThemeProvider } from './hooks/useTheme';
+import ErrorBoundary from './components/ErrorBoundary';
+import { Toaster } from './components/ui/sonner';
+import PullToRefresh from './components/PullToRefresh';
+import TopProgressBar from './components/TopProgressBar';
+
+/** 与路由无关的应用壳：Provider + 全局挂件（SSR 服务端 / 客户端共用） */
+export default function AppShell({ children }: { children: ReactNode }) {
+  return (
+    <ThemeProvider>
+      <AuthProvider>
+        <ErrorBoundary>
+          {children}
+          <TopProgressBar />
+          <PullToRefresh />
+          <Toaster />
+        </ErrorBoundary>
+      </AuthProvider>
+    </ThemeProvider>
+  );
+}