ci(pages): bump Pages actions off deprecated Node 20

[drawmeanelephant]

Agent Completion Report

• Status: complete
• Branch and Worktree:
  • Branch: ci/pages-actions-node24
  • Worktree: ci/pages-actions-node24 (main checkout)
• Commit and PR:
  • Commit: 04fda61e
  • Target PR / Branch: ci(pages): bump Pages actions off deprecated Node 20 #962 / main
• Linked Issues (auto-close convention):
  • None. No issue tracker card; this is a CI maintenance fix.
• Changed Files:
  • .github/workflows/github-pages.yml
  • docs/changelog.d/962-pages-actions-node24.md
• Preserved Unrelated Files:
  • No other tracked files were modified; local main was fast-forwarded to origin/main before branching, and no unrelated dirty state existed.
• Implementation Summary:
  • Pinned actions/configure-pages v5 → v6.0.0, actions/upload-pages-artifact v4 → v5.0.0, actions/upload-artifact v4 → v7.0.1, actions/download-artifact v4 → v8.0.1, and actions/deploy-pages v4 → v5.0.1, all Node 24 releases. Inputs used by the workflow are unchanged across majors.
  • Left actions/checkout (already Node 24 / v6) and mlugg/setup-zig (latest upstream v2.2.1, still Node 20) untouched.
  • Added the required changelog fragment linking the GitHub Pages target contract.
• Known Gaps:
  • mlugg/setup-zig v2.2.1 is the latest upstream release and still declares Node 20; no fix is available. The runner forces it onto Node 24 and it succeeds (a warning remains).
  • The deploy job could not be exercised from this topic branch: the github-pages environment only permits deployments from main (confirmed via the environment's deployment branch policy). deploy-pages v5.0.1 runs on main after merge. The download-artifact v8.0.1 path is behind the optional audit_deployment dispatch input and was not exercised.
• Exact Commands Run:
  1. gh api repos/drawmeanelephant/boris/pages (diagnosed the original 404)
  2. gh api -X POST repos/drawmeanelephant/boris/pages -f build_type=workflow (enabled Pages)
  3. zig build test
  4. gh workflow run github-pages.yml --ref ci/pages-actions-node24
  5. gh run watch 34702825037
• Exact Gate Results:
  • zig build test: pass
  • Pages build job (run 34702825037, branch ci/pages-actions-node24): pass — configure-pages v6, upload-pages-artifact v5, upload-artifact v7 all succeeded
  • Node 20 annotations after bump: only mlugg/setup-zig remains (upstream limitation)
  • Pages deploy job on branch: fail by design (environment permits main only)
• Determinism Result:
  • N/A — workflow pin change only.
• Generated Artifacts:
  • None. (Branch dispatch produced run 34702825037's build artifacts: github-pages and boris-github-pages-evidence-34702825037, retained by GitHub, not committed.)
• Blockers and Next Card:
  • Blockers: None
  • Next Card: After merge, confirm the GitHub Pages run on main completes build and deploy green with only the mlugg/setup-zig Node 20 warning remaining.