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

src/ClusterManager.php

@@ -203,12 +203,13 @@ class ClusterManager
      */
     public function isVirtualIpActive(string $vip): bool
     {
-        if ($vip === '') {
+        $cleanVip = explode('/', trim($vip))[0] ?? '';
+        if ($cleanVip === '') {
             return false;
         }
         $output = shell_exec('ip -o -4 addr show 2>/dev/null') ?: '';
         foreach (preg_split('/\r?\n/', $output) ?: [] as $line) {
-            if (preg_match('/\sinet\s+' . preg_quote($vip, '/') . '\//', $line)) {
+            if (preg_match('/\sinet\s+' . preg_quote($cleanVip, '/') . '(\/|\s)/', $line)) {
                 return true;
             }
         }