Fixes#291 - gastown is very hard to kill/shutdown/stop
Changes:
- Add shutdown coordination: daemon checks shutdown.lock and skips
heartbeat auto-restarts during shutdown to prevent fighting shutdown
- Add orphaned Claude/node process detection in shutdown verification
The daemon's heartbeat now checks for shutdown.lock (created by gt down)
and skips auto-restart logic when shutdown is in progress. This prevents
the daemon from restarting agents that were intentionally killed during
shutdown.
Shutdown verification now includes detection of orphaned Claude/node
processes that may be left behind when tmux sessions are killed but
child processes don't terminate.
65c1fad8ce