feat: add support for git branch

[hansonw]

Thanks for this tool! this implements https://github.com/mroth/scmpuff/issues/20 :)

Summary

• Implemented a new branch sub-command that prints git branches with numbers
  • Handles edge cases (e.g. running outside a git repo, detached HEAD)
• Added gb as an alias for scmpuff_branch in the initialization scripts
• Created shell wrapper functions to export numbered branch names for both Bash and Fish users
• Extended initialization to load the new branch functionality and updated the binary’s command list

Testing

• go test ./...
• make features (failed to find zsh during integration tests)

Example

[mroth]

Very cool! Thanks for such a detailed PR. It might take me a little while to review this, hopefully @hansonw you might be up for a few rounds of back and forth so we can figure out how this would interface with the broader refactor of the codebase? I really appreciate this!

[hansonw]

Thanks for reviewing! If you’re in the middle of a big refactor maybe it’s easier to just wait until after that lands to make this change?

full disclosure this PR was 95% generated by OpenAI Codex (which I work on ;)) so nbd to just do it again later!