Add internationalization scaffolding
Introduce an i18n layer (catalog, Preact context/hook, cookie +
Accept-Language middleware, and a /api/locale endpoint) so the site is
ready to ship additional languages. Only English is registered today;
the <LocaleSwitcher> self-hides until a second locale is added. All
user-facing copy across Nav, Hero, Features, Providers, Cross-pollination,
Moderation, Footer, AppShowcase, and DeveloperResources has been moved
into the typed message catalog so TypeScript enforces translation parity.
Made-with: Cursor