feat: Add tests for Wolf3dGuiApp and refactor game data picker management

- Introduced unit tests for the Wolf3dGuiApp to ensure proper directory configuration and audio management.
- Refactored the GameDataPickerManager to streamline directory and file selection processes.
- Removed obsolete GameDataPickerManager and Wolf3dAppManager classes to simplify the architecture.
- Enhanced the Wolf3dFlutterEngine to improve game version handling during save loading.
- Updated existing tests to reflect changes in the game data management structure.
- Removed unnecessary dependencies and cleaned up the codebase for better maintainability.

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

packages/wolf_3d_flutter/lib/widgets/wolf3d_app.dart

@@ -1,79 +0,0 @@
-library;
-
-import 'dart:async';
-
-import 'package:flutter/material.dart';
-import 'package:wolf_3d_flutter/wolf_3d_flutter.dart';
-
-/// Minimal app shell that binds a prepared [Wolf3dFlutterEngine] instance to
-/// host screens.
-class Wolf3dApp extends StatefulWidget {
-  /// Shared initialized facade that owns game data, input, and audio services.
-  final Wolf3dFlutterEngine engine;
-
-  const Wolf3dApp({
-    super.key,
-    required this.engine,
-  });
-
-  @override
-  State<Wolf3dApp> createState() => _Wolf3dAppState();
-}
-
-class _Wolf3dAppState extends State<Wolf3dApp> with WidgetsBindingObserver {
-  late final Wolf3dAppManager _manager;
-
-  @override
-  void initState() {
-    super.initState();
-    _manager = Wolf3dAppManager(engine: widget.engine);
-    WidgetsBinding.instance.addObserver(this);
-  }
-
-  @override
-  void dispose() {
-    WidgetsBinding.instance.removeObserver(this);
-    unawaited(_manager.ensureAudioShutdown());
-    super.dispose();
-  }
-
-  @override
-  void didChangeAppLifecycleState(AppLifecycleState state) {
-    if (state == AppLifecycleState.detached) {
-      unawaited(_manager.ensureAudioShutdown());
-    }
-  }
-
-  Future<void> _pickGameDataDirectory() {
-    return _manager.pickGameDataDirectory(
-      notifyChanged: () {
-        if (mounted) {
-          setState(() {});
-        }
-      },
-    );
-  }
-
-  Future<void> _pickGameDataFiles() {
-    return _manager.pickGameDataFiles(
-      notifyChanged: () {
-        if (mounted) {
-          setState(() {});
-        }
-      },
-    );
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    return widget.engine.availableGames.isEmpty
-        ? NoGameDataScreen(
-            configuredDataDirectory: widget.engine.configuredDataDirectory,
-            onPickGameDataDirectory: _pickGameDataDirectory,
-            onPickGameDataFiles: _pickGameDataFiles,
-            isLoadingGameData: _manager.isLoadingGameData,
-            pickerError: _manager.pickerError,
-          )
-        : GameScreen(wolf3d: widget.engine);
-  }
-}