- Removed unused CastleSide import from PgnExporter
- Updated TerminalUI and GUIObserver to use GameContext
- Temporarily disabled GUI FEN/PGN import-export (requires full rework with GameContext)
- Deleted unused logic files and GameController per spec
Note: GameEngine still needs final refactoring to use RuleSet + GameContext.
Core architecture (api -> rule -> core) is structurally complete.