Bump GitHub action versions and update README

Merged
SN
6d ago
+38-37

Summary by cubic

Bumps GitHub Action versions across all CI workflows and updates the README milestones.

  • Upgrades checkout, setup-node, cache, upload-artifact, configure-pages, upload-pages-artifact, deploy-pages, and stale to their latest versions.
  • Replaces codecov/test-results-action@v1 with codecov/codecov-action@v7 using report_type: test_results for test result uploads.
  • Updates the README roadmap: marks released milestones as complete and moves the stable release target to 2027 Q2.