fix: null-guard serverInfo in NatsProvisioner to fix unit tests

connection.getServerInfo() can return null (e.g. on a Mockito mock or before
the handshake completes). Guard both the version check and the log statement
so schedulingSupported defaults to false instead of NPE-ing.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: sonus21

rqueue-nats/src/main/java/com/github/sonus21/rqueue/nats/internal/NatsProvisioner.java

@@ -76,11 +76,12 @@ public NatsProvisioner(Connection connection, JetStreamManagement jsm, RqueueNat
     this.jsm = jsm;
     this.config = config;
     io.nats.client.api.ServerInfo serverInfo = connection.getServerInfo();
-    this.schedulingSupported = serverInfo.isSameOrNewerThanVersion(SCHEDULING_MIN_VERSION);
+    this.schedulingSupported =
+        serverInfo != null && serverInfo.isSameOrNewerThanVersion(SCHEDULING_MIN_VERSION);
     log.log(
         Level.INFO,
         "NATS server version={0}; message scheduling (ADR-51) supported={1}",
-        new Object[] {serverInfo.getVersion(), schedulingSupported});
+        new Object[] {serverInfo != null ? serverInfo.getVersion() : "unknown", schedulingSupported});
   }
 
   /** Returns {@code true} when the connected NATS server supports message scheduling (>= 2.12). */