[fank]

Summary

• Add --changed-from to build only new releases, changed archives and versions gaining tags.
• Apply selection to regular and rootless images; skip registry login when nothing changed.
• Pass before/after commit IDs from the scheduled updater and check out the exact updated commit.
• Rebuild all current versions for runtime/build-source changes or manual publication.

Closes #453.

Validation

• All 21 existing regression methods pass.
• actionlint validates both modified workflows; whitespace checks pass.
• Build-selection and workflow logic are unchanged from the previously validated implementation, including experimental-only updates, tag changes, runtime changes and missing baselines.
• Removed tests/test_changed_builds.py following maintainer feedback. No images were published during local validation.