includeCoAuthoredBy setting does not prevent hardcoded Claude Code attribution in commit messages

Issue Description

The includeCoAuthoredBy: false setting in Claude Code settings.json does not prevent Claude Code from adding attribution to git commit messages. Claude Code still automatically adds:

Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

This appears to be hardcoded behavior that bypasses the configuration setting.

Expected Behavior

When includeCoAuthoredBy: false is set, no Claude Code attribution should be added to commit messages.

Actual Behavior

Claude Code adds attribution regardless of the setting value.

Configuration

{
  "includeCoAuthoredBy": false
}

Request

Need a deterministic way to completely disable all Claude Code attribution in git commits and pull requests.