Validate UML artifacts in PRs instead of pushing to protected master

[Copilot]

The generate-uml workflow was failing because it attempted to push regenerated UML files directly to protected master. This updates the workflow to treat UML artifacts as checked-in outputs that must be refreshed in the PR branch.

• CI behavior

  • Run the UML workflow on pull requests targeting master
  • Generate doc-uml/ artifacts during CI
  • Fail the job when generated UML differs from the committed files, instead of attempting a direct push to the protected branch

• Contributor workflow

  • Document in README.md that changes under src/lib/famix/ may require committed updates to doc-uml/
  • Add the expected local update flow so contributors can refresh UML before updating the PR

• Failure guidance

  • Replace the branch-protection push failure with an explicit message telling contributors to regenerate and commit UML artifacts

- name: Fail if UML diagrams are outdated
  if: steps.check_changes.outputs.changed == 'true'
  run: |
    echo "Generated UML documentation is out of date."
    echo "Run 'npm run uml', commit the updated files in doc-uml/, and update this pull request."
    git diff -- doc-uml
    exit 1