Fix cluster not responding after restart

Two bugs prevented the cluster from working after a stop/start cycle:

1. tcp_listen_tcp() and tcp_listen_tls() had reuse_addr set to false,
   causing bind() to fail with EADDRINUSE when ports are in TIME_WAIT
   state after a restart. Set SO_REUSEADDR to true.

2. The vsr_boot_marker file (created in CWD on first boot) was never
   cleaned up on cluster stop. On restart, all nodes would enter
   STATUS_RECOVERY, but since RECOVERY messages are only processed by
   nodes in STATUS_NORMAL, the entire cluster would deadlock with no
   node able to recover. Remove the marker in cluster.sh stop.

https://claude.ai/code/session_01U72omHJrk95xFwm22Rkqgt

cluster.sh

@@ -138,6 +138,7 @@ do_stop() {
     stop_process "node1"
     stop_process "node2"
     stop_process "node3"
+    rm -f "$SCRIPT_DIR/vsr_boot_marker"
     echo "Cluster stopped."
 }