Migrate hosting from Netlify to Vercel

Summary

Migrate the site from Netlify to Vercel, and drop the Jekyll dependency entirely in favor of a zero-build static deploy.

Context

The site is currently deployed via Netlify, which auto-detects Jekyll from the Gemfile and _config.yml, runs jekyll build, and serves _site/ from the main branch. There is no netlify.toml — everything is inferred.

However, Jekyll is only used to render supporters.md via _layouts/supporters.html. Everything else (index.html, 404.html, images) is already fully static. The deployment architecture check (.continue/checks/deployment-architecture.md) already anticipates this migration.

What needs to happen

• Pre-render supporters.md to static HTML (or convert supporters.md to a self-contained supporters.html)
• Remove Jekyll dependencies (Gemfile, Gemfile.lock, _config.yml, _layouts/)
• Connect the repo to Vercel with no build command — just serve the repo root as static files
• Point the amplified.dev custom domain to Vercel
• Verify all pages, social cards, and discoverability files (llms.txt, robots.txt, sitemap.xml) work correctly
• Update the deployment architecture check to reflect Vercel as the current host
• Update README.md to reference Vercel instead of Netlify and remove the Jekyll development instructions

Why

Vercel with zero-build static deploy is simpler, removes the Ruby/Jekyll dependency entirely, and aligns with the site's philosophy of resisting unnecessary complexity.

Start with .continue/checks/deployment-architecture.md, the existing Jekyll files (Gemfile, Gemfile.lock, _config.yml, _layouts/), and README.md. Verify how supporters.md is rendered, then check the static pages and discoverability files listed in the issue. Done means the repository serves from Vercel without a build, the custom domain and pages work, and the documentation reflects the new deployment.