fix: preserve folder reference when renaming build world

Author: thomasmny

buildsystem-core/src/main/java/de/eintosti/buildsystem/world/WorldServiceImpl.java

@@ -323,6 +323,10 @@ public void renameWorld(Player player, BuildWorld buildWorld, String newName) {
         }
         Bukkit.unloadWorld(oldWorld, true);
         Bukkit.getWorlds().remove(oldWorld);
+
+        // Preserve folder reference before removing the world (since removeBuildWorld clears folder associations)
+        Folder previousFolder = buildWorld.getFolder();
+
         this.worldStorage.removeBuildWorld(buildWorld);
         Bukkit.getScheduler().runTaskAsynchronously(plugin, () -> this.worldStorage.delete(oldName));
 
@@ -338,6 +342,7 @@ public void renameWorld(Player player, BuildWorld buildWorld, String newName) {
             }
         }).thenRunAsync(() -> {
             buildWorld.setName(sanitizedNewName);
+            buildWorld.setFolder(previousFolder);
             worldStorage.addBuildWorld(buildWorld);
             worldStorage.save(buildWorld);
         }).thenRun(() -> Bukkit.getScheduler().runTask(plugin, () -> {