bridge restart now means blank-slate recovery: reverse tunnels run
should_cleanup_tunnel and clear orphan remote listeners before reconnecting;
healthy forwards are left running. Local-direction tunnels keep stop/start
only. CLI and MCP report per-tunnel actions (healthy, cleaned_and_restarted,
restarted, error) and exit non-zero on cleanup failure.
Closes BRIDGE-WP-0005.
Add bridge maintenance cleanup to detect reverse tunnels whose remote
port is bound but no longer forwards (zombie sshd sessions), kill the
stale listeners on the remote host, and optionally restart the tunnel.
Includes install-cron/uninstall-cron/show-cron helpers and README notes
for the actcore-state-hub-bridge failure mode we hit on railiance01.
