SoloLeveling999

### Added
- Added a new `/quest` command with support for `/quest <questname> cancel`.
- Added direct support for `/quest jobchange cancel` so players can cancel the Job Change quest and start it again later.

### Changed
- Job Change arena size is now doubled from the configured base size.
- Job Change arena is now built with oak wood only.
- Removed leaves from the Job Change arena structure to prevent despawn-related arena issues.
- Removed creepers from Job Change quest waves and Job Change spawner wave composition.
- Arena cleanup now removes arena blocks without dropping items.
- Arena protection was reinforced so players cannot break or place blocks in active arena regions.
- Arena protection was extended to prevent explosion and entity-driven block changes inside arena regions.