- Fix memory leaks in match3_gameplay.gd with proper queue_free() usage
- Add comprehensive error handling and fallback mechanisms to SettingsManager
- Resolve scene loading race conditions in GameManager with state protection
- Remove problematic static variables from tile.gd, replace with instance-based approach
- Consolidate duplicate debug menu classes into shared DebugMenuBase
- Add input validation across all user input paths for security and stability
