v0.1.0 — TanStack Start revamp

Major Changes

• Complete revamp: Nuxt 2 → TanStack Start + React 19 + Tailwind CSS v4 + shadcn/ui.
  Single-file site.config.ts, MDX articles with Shiki, RSS/sitemap/robots/llms.txt
  server routes, build-time OG images, dark/light theme (press d), mise-pinned
  toolchain, and Cloudflare Workers as the default deploy target with GitHub Actions
  auto-deploy. Firebase, i18n, PWA, and the newsletter API are gone.