feat: add churu holder; fix microsite links on preview deploys

[cdtinney]

Description

• Adds a new tool scenario — the Churu Holder — to the useyourdamnhands microsite.
• Rewrites microsite project links to the current origin when the page is served from a non-production host (Cloudflare Pages preview URLs, localhost). On tinney.dev / www.tinney.dev, links still point at the production microsite domain (useyourdamnhands.com).
• Earlier attempt used CF_PAGES_BRANCH / CF_PAGES_URL at build time — that does not work here because the build runs in GitHub Actions and wrangler pages deploy uploads a prebuilt artifact, so Cloudflare never sets those vars. This switches to a client-side rewrite driven by window.location.hostname + origin.
• Opt-in via an optional micrositePath field on the project entry; projects without it are unaffected.

Testing

• pnpm lint, pnpm format:check, pnpm typecheck, pnpm test (30 tests, incl. 6 for resolveProjectUrl), and pnpm build all pass locally
• Inspected built HTML: anchors carry data-microsite-path="/hands" and the hoisted inline script rewrites href when hostname isn't tinney.dev / www.tinney.dev
• Confirm on preview deploy: microsite project card links should now point at ${current-preview-host}/hands/, production should continue to point at useyourdamnhands.com

[github-actions]

Preview deployment

https://46cea71e.tinney-dev.pages.dev (b7c243d)

Previous previews

• https://6536ea1e.tinney-dev.pages.dev (86b02ba)
• https://027ab828.tinney-dev.pages.dev (1fe3d0c