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_cli/bin/main.dart

@@ -1,3 +1,9 @@
+/// CLI entry point for the terminal Wolf3D host.
+///
+/// This executable locates bundled retail assets, constructs a [WolfEngine]
+/// configured for terminal rendering, and then hands control to [CliGameLoop].
+library;
+
 import 'dart:io';
 
 import 'package:wolf_3d_cli/cli_game_loop.dart';
@@ -6,7 +12,7 @@ import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
 import 'package:wolf_3d_dart/wolf_3d_engine.dart';
 import 'package:wolf_3d_dart/wolf_3d_input.dart';
 
-// Helper to gracefully exit and restore the terminal
+/// Restores terminal state before exiting the process with [code].
 void exitCleanly(int code) {
   stdout.write('\x1b[0m'); // Reset color
   stdout.write('\x1b[2J\x1b[H'); // Clear screen
@@ -14,12 +20,13 @@ void exitCleanly(int code) {
   exit(code);
 }
 
+/// Launches the CLI renderer against the bundled retail asset set.
 void main() async {
   stdout.write("Discovering game data...");
-  // 1. Get the absolute URI of where this exact script lives
+  // Resolve the asset package relative to this executable so the CLI can run
+  // from the repo without additional configuration.
   final scriptUri = Platform.script;
 
-  // 2. Resolve the path mathematically.
   final targetUri = scriptUri.resolve(
     '../../../packages/wolf_3d_assets/assets/retail',
   );