[codex] fix site crawler checks

[zack-dev-cm]

Summary

Fixes the clawpatch.ai static site issues found during the debug pass:

• Adds robots.txt and sitemap.xml so crawler routes no longer 404 after deployment.
• Fixes the hero H1 spacing so extracted text reads Code review with explicit fixes.
• Adds a Node-based website:smoke check for static site metadata, crawler files, anchor targets, security-header config, and social-card dimensions.
• Adds _headers for hosts that support static header files.
• Widens the SIGTERM-resistant descendant timeout test timing so the full Vitest suite is stable under load.

Root Cause

The deployed site was missing crawler artifacts, and the H1 line break did not leave a space for text extraction. The existing test suite also had a timing-sensitive process test that could fail under full-suite load before its IPC-ready marker was written.

Validation

• pnpm test — 9 files passed, 623 tests passed, 1 skipped
• pnpm typecheck
• pnpm lint
• pnpm format:check
• pnpm website:smoke
• Local HTTP/browser check: homepage 200, /robots.txt 200, /sitemap.xml 200, normalized H1 correct, no console errors, no broken hash links

Deployment Note

Merging to main should publish the static site through the existing Pages flow. _headers only takes effect on hosts or CDNs that support header files; GitHub Pages itself does not apply it as response headers.