Use a dedicated thread pool for PWT event rescheduling

leaf-server/src/main/java/org/dreeam/leaf/async/world/PWTEventScheduler.java

@@ -0,0 +1,35 @@
+package org.dreeam.leaf.async.world;
+
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class PWTEventScheduler {
+    private static volatile PWTEventScheduler instance;
+    private final ExecutorService executor;
+    private PWTEventScheduler() {
+        this.executor = Executors.newCachedThreadPool(
+            new ThreadFactoryBuilder()
+                .setNameFormat("Leaf PWT Event Scheduler Thread - %d")
+                .setDaemon(true)
+                .setPriority(Thread.NORM_PRIORITY - 2)
+                .build()
+        );
+    }
+
+    public static PWTEventScheduler getScheduler() {
+        if (instance == null) {
+            synchronized (PWTEventScheduler.class) {
+                if (instance == null) {
+                    instance = new PWTEventScheduler();
+                }
+            }
+        }
+        return instance;
+    }
+
+    public void scheduleTask(Runnable task) {
+        this.executor.execute(task);
+    }
+}