Skip version bump when all changes are comment-only

[revarbat]

Summary

• Adds a new step to the Daily Version Stamp workflow that checks whether all changes since the last version bump are limited to // comment lines
• If every changed line (excluding version.scad) is a comment or blank, the version bump and commit are skipped
• Handles edge cases: no previous bump found (proceeds with bump), no non-version changes found (skips bump)

Test plan

• Merge a PR that only changes // comment lines in .scad files — verify the daily workflow does not bump the version
• Merge a PR with real code changes — verify the daily workflow does bump the version as before

🤖 Generated with Claude Code