Refactor menu rendering and improve projection sampling

- Updated AsciiRasterizer to support game and episode selection menus with improved layout and cursor handling.
- Enhanced SixelRasterizer and SoftwareRasterizer to modularize menu drawing logic for game and episode selection.
- Introduced new methods for drawing menus and applying fade effects across rasterizers.
- Adjusted wall texture sampling in Rasterizer to anchor to projection height center for consistent rendering.
- Added tests for wall texture sampling behavior to ensure legacy compatibility and new functionality.
- Modified Flutter audio adapter to use nullable access for active game and adjusted game selection logic in the main class.
- Cleaned up input handling in Wolf3dFlutterInput by removing unused menu tap variables.

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

apps/wolf_3d_cli/bin/main.dart

@@ -37,6 +37,14 @@ void main() async {
     recursive: true,
   );
 
+  if (availableGames.isEmpty) {
+    stderr.writeln('\nNo Wolf3D game files were found at: $targetPath');
+    stderr.writeln(
+      'Please provide valid game data files before starting the CLI host.',
+    );
+    exitCleanly(1);
+  }
+
   CliGameLoop? gameLoop;
 
   void stopAndExit(int code) {
@@ -45,7 +53,7 @@ void main() async {
   }
 
   final engine = WolfEngine(
-    data: availableGames.values.first,
+    availableGames: availableGames.values.toList(growable: false),
     startingEpisode: 0,
     frameBuffer: FrameBuffer(
       stdout.terminalColumns,