Description

Sync of #2007 to prerelease.

Original PR

Replace Algolia search with built-in search

Summary

• Algolia hosting is no longer available, so the navbar overlay search is broken. Switch to Quarto's built-in client-side search (the documented default — docs/websites/website-search.qmd), which reads the same _site/search.json Quarto already emits during render.
• Remove the algolia: blocks from _quarto.yml and _quarto-prerelease-docs.yml; the surviving show-item-context / type: overlay keys are honored by the built-in backend.
• Delete the supporting Algolia tooling: post-render index augmenter, Ruby uploader, upload-index / test-algolia-upload workflows, algolia-config.json, and the orphan search-by-algolia.png logo. Trim the matching bullet/row in .github/workflows/README.md and _tools/README.md so the inventory stays accurate.

Test plan

• Trigger the Netlify deploy preview (/deploy-preview comment, since this is a fork PR) and confirm the build succeeds with no post-render errors.
• On the preview site: open the navbar search overlay; query "callout", "yaml", "shortcode"; confirm results render from the local index with breadcrumbs (show-item-context: true) and that clicking a result navigates and ?q= highlight still works.
• After the auto-backport PR opens, repeat the same search check on the prerelease deploy preview.
• After merge: the repo's ALGOLIA_API_KEY secret can be deleted from Settings → Secrets, and the Algolia upload workflow won't appear in the Actions tab anymore.