The wrapper existed to add a git-specific env var to every command. Now
that that's gone, its New/NewShell/Quote methods just delegated to the
inner builder. The only remaining git-specific behavior — the command
runner — is attached in the constructor via CloneWithNewRunner, which
already returns a complete builder, so we can return that directly and
drop the wrapper struct.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>