DefaultWitnessHandler.HandleMerged was only logging a message but not
actually cleaning up the polecat worktree. This left worktrees behind
after merges, even though sessions were killed.
Fixed by calling witness.AutoNukeIfClean which:
- Verifies cleanup_status before nuking (prevents work loss)
- Calls NukePolecat to kill session, remove worktree, and cleanup
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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