Fix CI build failure by using workflow token for Jekyll GitHub metadata

[Copilot]

The build GitHub Actions job failed in Jekyll with 401 Bad credentials while fetching GitHub metadata. The workflow was wiring JEKYLL_GITHUB_TOKEN to a repository secret that was invalid in CI.

• Root cause

  • JEKYLL_GITHUB_TOKEN in the build step depended on secrets.JEKYLL_GITHUB_TOKEN, which was not valid for the failing run.

• Change

  • Switched the Jekyll build environment token source to the built-in workflow token (github.token) in .github/workflows/ci.yml.

• Impact

  • Removes dependency on a manually managed token for this step.
  • Aligns metadata auth with standard GitHub Actions token provisioning.

- name: Build with Jekyll
  env:
    JEKYLL_GITHUB_TOKEN: ${{ github.token }}
  run: bundle exec jekyll build