## Summary
- Fixes a bug where the response processor would attempt `git commit`
even when there were no staged changes, causing "nothing to commit"
errors
- Adds a `hasStagedChanges` utility function to `git_utils.ts` that
checks whether there are actually staged files before committing
- Updates the commit flow in `response_processor.ts` to check for staged
changes first, skipping the commit when unnecessary

## Test plan
- [x] All 897 existing tests pass
- [x] Lint, formatting, and type checks pass
- Verify that file write/rename/delete operations still commit correctly
when changes are staged
- Verify that no error is thrown when git operations result in no staged
changes

🤖 Generated with [Claude Code](https://claude.com/claude-code)
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---------
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: Will Chen <willchen90@gmail.com>