Migrate GH Pages deploy to artifact-based deployment

[mmcky]

Summary

Migrates GitHub Pages deployment from the gh-pages branch (peaceiris/actions-gh-pages) to native artifact-based deployment, following the QuantEcon infrastructure guide in QuantEcon/meta#282. lecture-python-programming was migrated the same way in QuantEcon/lecture-python-programming#499. Once the gh-pages branch is deleted (final step, after verification), the repo drops from ~767 MB to ~15 MB.

This PR only touches the two workflow files. Merging it changes nothing on the live site — the site keeps serving from gh-pages until we flip the Pages source in repo Settings (a manual post-merge step). So there is no downtime window from merging.

What changed

publish.yml

• Adds a top-level permissions block, a pages concurrency group, and the github-pages environment on the job.
• Replaces the peaceiris/actions-gh-pages@v4 step with configure-pages@v6 + upload-pages-artifact@v5 + deploy-pages@v5, writing intro.quantecon.org into _build/html/CNAME first.
• The Netlify deploy, release-asset upload, _build cache upload, and notebook sync are all left untouched.

linkcheck.yml

• Replaces the gh-pages checkout (which won't exist after migration) with a download of the latest release .tar.gz, and swaps lychee for QuantEcon/action-link-checker@main — matching the standard now used by lecture-python-programming.

Note on the permissions block

The workflow previously ran with the default permissive token. Because specifying permissions: resets every unlisted scope to none, the block enumerates everything this workflow actually needs. Two entries are specific to this repo (the programming reference did not need them):

Permission	Why it is required here
contents: write	Release-asset upload (softprops/action-gh-release) and Netlify commit comment
actions: read	dawidd6/action-download-artifact pulls the build-cache artifact from cache.yml
statuses: write	Netlify step posts a commit status
pages: write	actions/deploy-pages
id-token: write	OIDC token required by actions/deploy-pages

Post-merge steps (manual — do NOT skip the order)

Per QuantEcon/meta#282 §7.2, after this merges:

1. Settings → Pages → set Source to GitHub Actions.
2. Settings → Environments → github-pages → add a Tag deployment rule publish* (without this the first tag deploy fails with "Tag is not allowed to deploy… due to environment protection rules").
3. Push a test publish-* tag and watch the run.
4. Verify: site loads, build_type: workflow, release assets attached, notebook sync ran, Netlify deployed.
5. Run linkcheck via workflow_dispatch and confirm it downloads the release asset.
6. Delete the gh-pages branch and notify the team to prune locally.

Rollback

If anything looks wrong before step 6: Settings → Pages → Source → "Deploy from a branch" → gh-pages, and the site immediately serves from the old branch again.

🤖 Generated with Claude Code

[netlify]

✅ Deploy Preview for taupe-gaufre-c4e660 ready!

Name	Link
🔨 Latest commit	51c25b5
🔍 Latest deploy log	https://app.netlify.com/projects/taupe-gaufre-c4e660/deploys/6a4afb2bad3710000852fec7
😎 Deploy Preview	https://deploy-preview-783--taupe-gaufre-c4e660.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[Copilot]

Pull request overview

Migrates GitHub Pages publishing from a gh-pages branch deployment to the native artifact-based Pages deployment flow, and updates link checking to operate on the latest release HTML archive (rather than checking out gh-pages) as part of the planned branch deletion/size reduction.

Changes:

• Update publish.yml to deploy via actions/configure-pages + actions/upload-pages-artifact + actions/deploy-pages, including explicit workflow permissions and a Pages concurrency group.
• Update linkcheck.yml to download and extract the latest release .tar.gz HTML archive and run QuantEcon/action-link-checker.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
.github/workflows/publish.yml	Switches Pages deployment from peaceiris/actions-gh-pages to artifact-based Pages deployment with explicit permissions/concurrency.
.github/workflows/linkcheck.yml	Replaces gh-pages checkout + lychee with “download latest release HTML” + QuantEcon link checker.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[github-actions]

🚀 Deployed on https://6a4afcfb100497bc65dcc086--taupe-gaufre-c4e660.netlify.app

[mmcky]

Addressed Copilot's 4 comments in 51c25b5:

• Added contents: read for the gh api releases call (①)
• set -euo pipefail + single-asset selection + fail-fast when no .tar.gz is found (②)
• curl -fsSL so download errors fail the step instead of piping into tar (③)
• Kept QuantEcon/action-link-checker@main — first-party org action, matches lecture-python-programming (④, replied with rationale)

The three hardening changes were filed for the identical workflow in lecture-python-programming as QuantEcon/lecture-python-programming#566 to keep both repos in sync.