v0.3.0

Release v0.3.0: Mobile-optimized Reversi with enhanced game flow

- Complete game flow redesign: Loading → Language Selection → Difficulty Selection → Playing
- Asynchronous AI system preventing UI blocking during computation
- Mobile-optimized touch interface with 44px minimum button targets
- Player avatars that match their piece colors (black/white)
- Random initial piece color variation for gameplay variety

- Enhanced entity cleanup system for proper state transitions
- Performance optimizations with Changed<T> filters
- Better mobile UI with 400x600 resolution optimization
- Comprehensive button interaction system
- Fixed AI thinking indicator with stable layout

- Upgraded to Bevy 0.16
- Async AI using AsyncComputeTaskPool
- Improved code quality passing all Clippy checks
- Better touch input handling for web mobile
- Internationalization support (English/Chinese)