Add CI Docker build verification job in main CI workflow

[Copilot]

This updates CI to fail fast when the Docker environment becomes non-buildable. The workflow now validates the Docker build path used by the project without publishing artifacts.

• Workflow scope

  • Extended .github/workflows/ci.yml with a dedicated docker-build-check job on the existing push/pull_request triggers (main, gh-pages).

• Docker build verification

  • Added a non-push build step that exercises docker/Dockerfile directly:

  docker-build-check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Build Docker image
        run: docker build -f docker/Dockerfile .

• Workflow security hardening

  • Added explicit minimal token permissions at workflow level:

  permissions:
    contents: read

[Copilot]

Pull request overview

This PR strengthens the existing CI pipeline by adding a lightweight Docker build verification job to ensure the repository’s docker/Dockerfile remains buildable, and by explicitly restricting GitHub token permissions to read-only for improved workflow security.

Changes:

• Added workflow-level minimal permissions (contents: read).
• Added a new docker-build-check job that runs docker build -f docker/Dockerfile . on push/pull_request to main and gh-pages.

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