feat: SEO optimization, favicons, and dark mode download button fix

- Add comprehensive metadata: Open Graph, Twitter Card, keywords, robots
- Add per-page metadata with i18n alternates for homepage (en/zh)
- Add robots.ts, sitemap.ts (dynamic from docs), manifest.ts
- Add favicon (icon.png 32px), apple-icon.png (180px), PWA icons (192/512px)
- Add og-image.png (1200x630) for social sharing
- Update site.config.ts with canonical URL and improved description
- Fix DownloadButton dark mode: white-on-white text → dark:bg-white dark:text-black

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

apps/site/src/app/[lang]/(marketing)/page.tsx

@@ -1,3 +1,4 @@
+import type { Metadata } from 'next';
 import { getMarketingContent } from '../../../../content/marketing';
 import { ScrollNav } from '@/components/marketing/ScrollNav';
 import { HeroSection } from '@/components/marketing/HeroSection';
@@ -6,6 +7,31 @@ import { IntegrationsSection } from '@/components/marketing/IntegrationsSection'
 import { FAQSection } from '@/components/marketing/FAQAccordion';
 import { FinalCTA } from '@/components/marketing/FinalCTA';
 import { SiteFooter } from '@/components/marketing/SiteFooter';
+import { siteConfig } from '@/lib/site.config';
+
+export async function generateMetadata({
+  params,
+}: {
+  params: Promise<{ lang: string }>;
+}): Promise<Metadata> {
+  const { lang } = await params;
+  const isZh = lang === 'zh';
+  return {
+    title: isZh
+      ? 'CodePilot — Claude Code 的桌面工作空间'
+      : 'CodePilot — Desktop Workspace for Claude Code',
+    description: isZh
+      ? '将对话、Provider、MCP、Skills 和项目上下文整合到一个桌面界面中。'
+      : siteConfig.description,
+    alternates: {
+      canonical: isZh ? `${siteConfig.url}/zh` : siteConfig.url,
+      languages: {
+        en: siteConfig.url,
+        zh: `${siteConfig.url}/zh`,
+      },
+    },
+  };
+}
 
 export default async function HomePage({
   params,

apps/site/src/app/layout.tsx

@@ -1,13 +1,64 @@
 import './global.css';
 import type { ReactNode } from 'react';
 import type { Metadata } from 'next';
+import { siteConfig } from '@/lib/site.config';
+
+const title = {
+  default: 'CodePilot — Desktop Workspace for Claude Code',
+  template: '%s | CodePilot',
+};
+
+const description = siteConfig.description;
 
 export const metadata: Metadata = {
-  title: {
-    default: 'CodePilot',
-    template: '%s | CodePilot',
+  title,
+  description,
+  metadataBase: new URL(siteConfig.url),
+  keywords: [
+    'Claude Code',
+    'AI coding',
+    'desktop app',
+    'MCP',
+    'Claude',
+    'Anthropic',
+    'code assistant',
+    'AI agent',
+  ],
+  authors: [{ name: 'CodePilot' }],
+  creator: 'CodePilot',
+  openGraph: {
+    type: 'website',
+    locale: 'en_US',
+    url: siteConfig.url,
+    siteName: siteConfig.name,
+    title: title.default,
+    description,
+    images: [
+      {
+        url: '/og-image.png',
+        width: 1200,
+        height: 630,
+        alt: 'CodePilot — Desktop Workspace for Claude Code',
+      },
+    ],
+  },
+  twitter: {
+    card: 'summary_large_image',
+    title: title.default,
+    description,
+    images: ['/og-image.png'],
+  },
+  robots: {
+    index: true,
+    follow: true,
+    googleBot: {
+      index: true,
+      follow: true,
+      'max-video-preview': -1,
+      'max-image-preview': 'large',
+      'max-snippet': -1,
+    },
   },
-  description: 'A native desktop GUI client for Claude Code',
 };
 
 export default function RootLayout({ children }: { children: ReactNode }) {

apps/site/src/app/manifest.ts

@@ -0,0 +1,17 @@
+import type { MetadataRoute } from 'next';
+
+export default function manifest(): MetadataRoute.Manifest {
+  return {
+    name: 'CodePilot',
+    short_name: 'CodePilot',
+    description: 'Desktop workspace for Claude Code',
+    start_url: '/',
+    display: 'browser',
+    background_color: '#ffffff',
+    theme_color: '#2563eb',
+    icons: [
+      { src: '/icon-192.png', sizes: '192x192', type: 'image/png' },
+      { src: '/icon-512.png', sizes: '512x512', type: 'image/png' },
+    ],
+  };
+}

apps/site/src/app/robots.ts

@@ -0,0 +1,14 @@
+import type { MetadataRoute } from 'next';
+import { siteConfig } from '@/lib/site.config';
+
+export default function robots(): MetadataRoute.Robots {
+  return {
+    rules: [
+      {
+        userAgent: '*',
+        allow: '/',
+      },
+    ],
+    sitemap: `${siteConfig.url}/sitemap.xml`,
+  };
+}

apps/site/src/app/sitemap.ts

@@ -0,0 +1,26 @@
+import type { MetadataRoute } from 'next';
+import { source } from '@/lib/source';
+import { siteConfig } from '@/lib/site.config';
+
+export default function sitemap(): MetadataRoute.Sitemap {
+  const url = siteConfig.url;
+
+  const staticPages: MetadataRoute.Sitemap = [
+    { url, lastModified: new Date(), changeFrequency: 'weekly', priority: 1 },
+    { url: `${url}/zh`, lastModified: new Date(), changeFrequency: 'weekly', priority: 0.9 },
+  ];
+
+  const docPages: MetadataRoute.Sitemap = source.getPages().map((page) => {
+    const lang = page.locale ?? 'en';
+    const slugPath = page.slugs.join('/');
+    const prefix = lang === 'en' ? '' : `/${lang}`;
+    return {
+      url: `${url}${prefix}/docs/${slugPath}`,
+      lastModified: new Date(),
+      changeFrequency: 'weekly' as const,
+      priority: 0.7,
+    };
+  });
+
+  return [...staticPages, ...docPages];
+}

apps/site/src/components/docs/DownloadButton.tsx

@@ -6,7 +6,7 @@ export function DownloadButton({ label = 'Download Latest Release' }: { label?:
       href={`${siteConfig.repo.releases}/latest`}
       target="_blank"
       rel="noopener noreferrer"
-      className="mt-4 mb-6 inline-flex items-center gap-2 rounded-full bg-foreground px-6 py-3 text-sm font-semibold text-background transition-opacity hover:opacity-80"
+      className="mt-4 mb-6 inline-flex items-center gap-2 rounded-full bg-foreground px-6 py-3 text-sm font-semibold text-background transition-opacity hover:opacity-80 dark:bg-white dark:text-black"
     >
       {label}
       <span aria-hidden="true">→</span>

apps/site/src/lib/site.config.ts

@@ -5,7 +5,8 @@
  */
 export const siteConfig = {
   name: 'CodePilot',
-  description: 'A native desktop GUI client for Claude Code',
+  description: 'Desktop workspace for Claude Code — conversations, providers, MCP, and project context in one place.',
+  url: 'https://www.codepilot.sh',
 
   // Canonical repository
   repo: {