Refactor and enhance documentation across the Wolf3D project

- Updated library imports to use the correct package paths for consistency.
- Added detailed documentation comments to various classes and methods, improving code readability and maintainability.
- Refined the GameSelectScreen, SpriteGallery, and VgaGallery classes with clearer descriptions of their functionality.
- Enhanced the CliInput class to better explain the input handling process and its interaction with the engine.
- Improved the SixelRasterizer and Opl2Emulator classes with comprehensive comments on their operations and state management.
- Removed the deprecated wolf_3d.dart file and consolidated its functionality into wolf_3d_flutter.dart for a cleaner architecture.
- Updated the Wolf3dFlutterInput class to clarify its role in merging keyboard and pointer events.
- Enhanced the rendering classes to provide better context on their purpose and usage within the Flutter framework.

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_dart/lib/wolf_3d_data.dart

@@ -1,6 +1,8 @@
-/// Support for doing something awesome.
+/// Public data-loading exports for Wolfenstein 3D assets.
 ///
-/// More dartdocs go here.
+/// This library exposes the low-level parser and the higher-level loader used
+/// to discover, validate, and decode original game data files into strongly
+/// typed Dart models.
 library;
 
 export 'src/data/wl_parser.dart' show WLParser;