Document what a harness is (private repo containing GT installation), why you would want one (work on public projects privately), and how to configure beads redirects for multi-rig workflows. Closes: gt-346, gt-5qc, gt-l1o 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>