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_renderer/lib/base_renderer.dart

@@ -1,21 +1,30 @@
+/// Shared Flutter renderer shell for driving the Wolf3D engine from a widget tree.
+library;
+
 import 'package:flutter/material.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:wolf_3d_dart/wolf_3d_engine.dart';
 
-// 1. The widget now only requires the engine!
+/// Base widget for renderers that present frames from a [WolfEngine].
 abstract class BaseWolfRenderer extends StatefulWidget {
+  /// Engine instance that owns world state and the shared framebuffer.
   final WolfEngine engine;
 
+  /// Creates a renderer bound to [engine].
   const BaseWolfRenderer({
     required this.engine,
     super.key,
   });
 }
 
+/// Base [State] implementation that provides a ticker-driven render loop.
 abstract class BaseWolfRendererState<T extends BaseWolfRenderer>
     extends State<T>
     with SingleTickerProviderStateMixin {
+  /// Per-frame ticker used to advance the engine and request renders.
   late final Ticker gameLoop;
+
+  /// Focus node used by the enclosing [KeyboardListener].
   final FocusNode focusNode = FocusNode();
 
   Duration _lastTick = Duration.zero;
@@ -50,8 +59,13 @@ abstract class BaseWolfRendererState<T extends BaseWolfRenderer>
     super.dispose();
   }
 
+  /// Renders the latest engine state into the concrete renderer's output type.
   void performRender();
+
+  /// Builds the visible viewport widget for the latest rendered frame.
   Widget buildViewport(BuildContext context);
+
+  /// Background color used by the surrounding scaffold.
   Color get scaffoldColor;
 
   @override