Add per-page metadata, Open Graph / Twitter tags, canonical URLs,
hreflang, sitemap generation, robots.txt, and JSON-LD structured data
for the bilingual (en/cn) documentation site.
- Extract LandingNav into shared component with lang/active props
- Add Home and Community nav items with active state highlighting
- Deepen landing background (#0b1120), strengthen hero glow, add CSS noise texture
- Sync changelog page to use shared nav and semantic colors
- Create /[lang]/community page with QQ, WeChat, Discord, GitHub Discussions
t8y2