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/sprite_gallery.dart

@@ -1,12 +1,18 @@
+/// Visual browser for decoded sprite assets and their inferred gameplay roles.
+library;
+
 import 'package:flutter/material.dart';
 import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
 import 'package:wolf_3d_dart/wolf_3d_entities.dart';
-import 'package:wolf_3d_flutter/wolf_3d.dart';
+import 'package:wolf_3d_flutter/wolf_3d_flutter.dart';
 import 'package:wolf_3d_renderer/wolf_3d_asset_painter.dart';
 
+/// Displays every sprite frame in the active game along with enemy metadata.
 class SpriteGallery extends StatelessWidget {
+  /// Shared application facade used to access the active game's sprite set.
   final Wolf3d wolf3d;
 
+  /// Creates the sprite gallery for [wolf3d].
   const SpriteGallery({super.key, required this.wolf3d});
 
   bool get isShareware => wolf3d.activeGame.version == GameVersion.shareware;
@@ -29,6 +35,8 @@ class SpriteGallery extends StatelessWidget {
         itemBuilder: (context, index) {
           String label = "Sprite Index: $index";
           for (final enemy in EnemyType.values) {
+            // The gallery infers likely ownership from sprite index ranges so
+            // debugging art packs does not require cross-referencing source.
             if (enemy.claimsSpriteIndex(index, isShareware: isShareware)) {
               final EnemyAnimation? animation = enemy.getAnimationFromSprite(
                 index,