v0.4.0

Added

• git_checkpoint_list — list the session's checkpoint snapshots, newest first, so an earlier one can be selected for restore. git_checkpoint_restore now accepts a checkpoint argument (a sha from the list) to roll back to any recorded snapshot instead of only the latest.
• Automated release pipeline (.github/workflows/release.yml): on a v* tag push, verify the tag matches the package version, run npm run check, publish to npm with provenance, and create a GitHub Release with changelog notes plus the packed tarball.