fix(cluster): strict SIP isolation on standby node and progressive BLF wake on master to eliminate stuck BLF lights

scripts/nexus-cluster

@@ -53,6 +53,8 @@ case "$CMD" in
     stop)
         systemctl stop keepalived >/dev/null 2>&1 || true
         systemctl disable keepalived >/dev/null 2>&1 || true
+        iptables -D INPUT -p udp -m multiport --dports 5060,5061 -j REJECT --reject-with icmp-port-unreachable 2>/dev/null || true
+        iptables -D INPUT -p tcp -m multiport --dports 5060,5061 -j REJECT --reject-with tcp-reset 2>/dev/null || true
         echo "KEEPALIVED_STOPPED_OK"
         ;;