Fixed
- **World folders now created at server root** — `WorldCreator` was using an implicit `minecraft:` namespace, causing newer Paper/Purpur builds to store resource worlds as sub-dimensions inside `world/dimensions/minecraft/` instead of as top-level folders. Switched to `WorldCreator.ofKey(new NamespacedKey(plugin, name))` so the dimension key becomes `bubblereset:resource_world`, which Paper correctly resolves to a standalone world folder at the server root. Fix applies to both initial world creation and post-reset recreation.