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>

apps/wolf_3d_gui/lib/screens/vga_gallery.dart

@@ -1,10 +1,16 @@
+/// Visual browser for decoded VGA pictures and UI art.
+library;
+
 import 'package:flutter/material.dart';
 import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
 import 'package:wolf_3d_renderer/wolf_3d_asset_painter.dart';
 
+/// Shows each VGA image extracted from the currently selected game data set.
 class VgaGallery extends StatelessWidget {
+  /// Raw VGA images decoded from the active asset pack.
   final List<VgaImage> images;
 
+  /// Creates the gallery for [images].
   const VgaGallery({super.key, required this.images});
 
   @override