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- Added SaveGameCodec for encoding and decoding save game files. - Introduced SaveGamePersistence interface for slot-based save game persistence. - Implemented FlutterSaveGamePersistence for file-based save management on Flutter. - Enhanced WolfEngine to support saving and loading game states. - Updated menu manager to include save/load game options. - Created tests for SaveGameCodec to ensure proper functionality. Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>