feat: Implement save game functionality with encoding/decoding

- 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>

apps/wolf_3d_cli/bin/main.dart

@@ -8,6 +8,7 @@ import 'dart:io';
 
 import 'package:wolf_3d_cli/cli_game_loop.dart';
 import 'package:wolf_3d_cli/cli_renderer_settings_persistence.dart';
+import 'package:wolf_3d_cli/cli_save_game_persistence.dart';
 import 'package:wolf_3d_dart/wolf_3d_data.dart';
 import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
 import 'package:wolf_3d_dart/wolf_3d_engine.dart';
@@ -63,6 +64,7 @@ void main() async {
     input: CliInput(),
     onGameWon: () => stopAndExit(0),
     onQuit: () => stopAndExit(0),
+    saveGamePersistence: CliSaveGamePersistence(),
   );
 
   engine.init();