Preserve state when switching renderers

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

apps/wolf_3d_gui/lib/screens/game_screen.dart

@@ -33,10 +33,7 @@ class _GameScreenState extends State<GameScreen> {
   @override
   void initState() {
     super.initState();
-
     _input = Wolf3dFlutterInput();
-
-    // The Host Screen owns the engine lifecycle
     _engine = WolfEngine(
       data: widget.data,
       difficulty: widget.difficulty,
@@ -45,7 +42,6 @@ class _GameScreenState extends State<GameScreen> {
       input: _input,
       onGameWon: () => Navigator.of(context).pop(),
     );
-
     _engine.init();
   }
 
@@ -54,20 +50,17 @@ class _GameScreenState extends State<GameScreen> {
     return Scaffold(
       body: Stack(
         children: [
-          // Render the active view
           _useAsciiMode
               ? WolfAsciiRenderer(engine: _engine)
               : WolfFlutterRenderer(engine: _engine),
 
-          // Invisible listener to trap the 'Tab' key and swap renderers
+          // TAB listener
           Focus(
-            autofocus: false,
+            autofocus: true,
             onKeyEvent: (node, event) {
               if (event is KeyDownEvent &&
                   event.logicalKey == LogicalKeyboardKey.tab) {
-                setState(() {
-                  _useAsciiMode = !_useAsciiMode;
-                });
+                setState(() => _useAsciiMode = !_useAsciiMode);
                 return KeyEventResult.handled;
               }
               return KeyEventResult.ignored;
@@ -75,16 +68,21 @@ class _GameScreenState extends State<GameScreen> {
             child: const SizedBox.shrink(),
           ),
 
-          // Optional: A little UI hint
+          // Loading Overlay
+          if (!_engine.isInitialized)
+            Container(
+              color: Colors.black,
+              child: const Center(
+                child: CircularProgressIndicator(color: Colors.teal),
+              ),
+            ),
+
           Positioned(
             top: 16,
             right: 16,
             child: Text(
-              'Press TAB to swap renderers',
-              style: TextStyle(
-                color: Colors.white.withValues(alpha: 0.5),
-                fontSize: 12,
-              ),
+              'TAB: Swap Renderer',
+              style: TextStyle(color: Colors.white.withValues(alpha: 0.5)),
             ),
           ),
         ],