Replace environment-specific fallback '/Users/gavriel' with os.homedir()
and proper error handling. The new getHomeDir() helper function:
- First checks process.env.HOME
- Falls back to os.homedir() for cross-platform support
- Throws a clear error if home directory cannot be determined
https://claude.ai/code/session_011Cs2FWxXMvAdAh4w9A6AZC
