Previously, gt doctor --fix would kill workers whose spawning process had
exited, even though the Claude session was still running in tmux.
Now both identity_check.go and CleanStaleLocks check if the tmux session
exists before declaring a lock stale. A lock is only truly stale if BOTH
the PID is dead AND the session does not exist.
Also added ListSessionIDs() to tmux package to handle locks that store
session IDs (%N or $N format) instead of session names.
- internal/lock: New package with PID-based lockfiles for worker identity
- gt prime: Acquire identity lock for crew/polecat roles, fail on collision
- gt agents check: Detect stale locks and identity collisions
- gt agents fix: Clean up stale locks
- gt doctor: New identity-collision check with --fix support
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
