fix(cluster): ensure only VIP holder pushes sync and prevent deadlocks with flock and strict VIP check

public/api.php

@@ -1798,7 +1798,8 @@ try {
             try {
                 $cm = new ClusterManager($db);
                 $cSet = $cm->getSettings();
-                if (!empty($cSet['enabled']) && !empty($cSet['auto_sync']) && ($cSet['role'] ?? '') === 'master' && !empty($cSet['peer_ip'])) {
+                $isVipActive = $cm->isVirtualIpActive($cSet['virtual_ip'] ?? '');
+                if (!empty($cSet['enabled']) && !empty($cSet['auto_sync']) && $isVipActive && !empty($cSet['peer_ip'])) {
                     $syncRes = $cm->pushSyncToPeer();
                     $clusterSyncMsg = $syncRes['message'] ?? 'Réplication pair OK';
                 }