feat: 官网补充公司主体信息与隐私政策、服务条款页

新增 /privacy、/terms 页面，提供英文与印尼文版本，覆盖 Google 登录数据、Play 内购与订阅、账号删除及印尼个人数据保护要求；关于页补充法定主体、注册地址与联系方式，页脚下沉法律入口，下载区仅保留 Google Play。

src/layouts/AppShell.jsx

@@ -1,17 +1,24 @@
 // Author: fruit.com.cn
 import { Suspense, useState } from 'react';
-import { Outlet, useLocation } from 'react-router-dom';
+import { Link, Outlet, useLocation } from 'react-router-dom';
 import { useLocale, useUi } from '../app/providers/AppProviders';
 import { Sidebar } from './components/Sidebar';
 import { TopBar } from './components/TopBar';
 import { UploadVideoDialog } from './components/UploadVideoDialog';
 
+const FOOTER_LINKS = {
+  id: { privacy: 'Privasi', terms: 'Ketentuan', about: 'Tentang YMB' },
+  en: { privacy: 'Privacy', terms: 'Terms', about: 'About YMB' },
+  zh: { privacy: '隐私政策', terms: '服务条款', about: '关于 YMB' },
+};
+
 export function AppShell() {
   const { locale } = useLocale();
   const { sidebarOpen, setSidebarOpen } = useUi();
   const location = useLocation();
   const [uploadOpen, setUploadOpen] = useState(false);
   const immersive = location.pathname === '/shorts';
+  const links = FOOTER_LINKS[locale.code] || FOOTER_LINKS.en;
 
   return (
     <>
@@ -21,7 +28,18 @@ export function AppShell() {
         <Suspense fallback={<div className="route-loading" aria-busy="true" />}>
           <Outlet />
         </Suspense>
-        {!immersive && <footer className="site-footer">© {new Date().getFullYear()} {locale.copyright}</footer>}
+        {!immersive && (
+          <footer className="site-footer">
+            <div>© {new Date().getFullYear()} {locale.copyright}</div>
+            <nav className="site-footer-links" aria-label="Legal and company information">
+              <Link to="/privacy">{links.privacy}</Link>
+              <span aria-hidden="true">·</span>
+              <Link to="/terms">{links.terms}</Link>
+              <span aria-hidden="true">·</span>
+              <Link to="/about">{links.about}</Link>
+            </nav>
+          </footer>
+        )}
       </main>
       {sidebarOpen && (
         <button className="scrim mobile-only" onClick={() => setSidebarOpen(false)} aria-label="Close" type="button" />