Migrate CI from Travis to GitHub Actions and align CV skills metadata

[Copilot]

This updates the repository from Travis CI to GitHub Actions and removes stale Travis references from the CV data. It preserves the existing Docker-based verification flow while tightening workflow permissions and failure diagnostics.

• CI platform migration

  • Added .github/workflows/ci.yml to replace Travis.
  • Kept parity with prior checks: build html2x and logo images, then run both containers.
  • Removed .travis.yml.

• Workflow security and operability

  • Added explicit least-privilege token scope:
    • permissions: { contents: read }
  • Improved failure triage:
    • emit docker ps -a
    • fetch container logs only when the container exists.

• Docker build compatibility

  • Updated html2x/Dockerfile base image from debian:stable-slim to debian:bookworm-slim so required packages resolve consistently in CI.

• CV skill taxonomy cleanup

  • Updated _config.yml skills list:
    • removed travis
    • added actions, github, containers
    • retained docker.

permissions:
  contents: read

- docker
- containers
- actions
- github