Refactor audio module to use built-in music and sound effect identifiers

- Introduced BuiltInMusicModule and BuiltInSfxModule to replace RetailMusicModule and RetailSfxModule.
- Updated RetailAssetRegistry and SharewareAssetRegistry to utilize the new built-in modules.
- Removed deprecated MusicKey and SfxKey classes, replacing them with Music and SoundEffect enums for better clarity and maintainability.
- Adjusted music and sound effect resolution methods to align with the new structure.
- Updated audio playback methods in WolfAudio and FlutterAudioAdapter to accept the new Music and SoundEffect types.
- Refactored tests to accommodate changes in audio event handling and ensure compatibility with the new identifiers.

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

packages/wolf_3d_dart/lib/src/synth/wolf_3d_audio.dart

@@ -13,7 +13,7 @@ class WolfAudio implements EngineAudio {
     for (int i = 0; i < 50; i++) {
       Future.delayed(Duration(seconds: i * 2), () {
         log("[AUDIO] Testing Sound ID: $i");
-        playSoundEffect(i);
+        playSoundEffectId(i);
       });
     }
   }
@@ -122,16 +122,21 @@ class WolfAudio implements EngineAudio {
   @override
   Future<void> playMenuMusic() async {
     final data = activeGame;
-    if (data == null || data.music.length <= 1) return;
-    await playMusic(data.music[1]);
+    final trackIndex = data == null
+        ? null
+        : Music.menuTheme.trackIndexFor(data.version);
+    if (data == null || trackIndex == null || trackIndex >= data.music.length) {
+      return;
+    }
+    await playMusic(data.music[trackIndex]);
   }
 
   @override
-  Future<void> playLevelMusic(WolfLevel level) async {
+  Future<void> playLevelMusic(Music music) async {
     final data = activeGame;
     if (data == null || data.music.isEmpty) return;
 
-    final index = level.musicIndex;
+    final index = music.trackIndexFor(data.version) ?? 0;
     if (index < data.music.length) {
       await playMusic(data.music[index]);
     } else {
@@ -144,14 +149,24 @@ class WolfAudio implements EngineAudio {
   // ==========================================
 
   @override
-  Future<void> playSoundEffect(int sfxId) async {
+  Future<void> playSoundEffect(SoundEffect effect) async {
+    final data = activeGame;
+    if (data == null) return;
+    await playSoundEffectId(effect.idFor(data.version));
+  }
+
+  @override
+  Future<void> playSoundEffectId(int sfxId) async {
     log("[AUDIO] Playing sfx id $sfxId");
     // The original engine uses a specific starting chunk for digitized sounds.
     // In many loaders, the 'sounds' list is already just the digitized ones.
     // If your list contains EVERYTHING, you need to add the offset (174).
     // If it's JUST digitized sounds, sfxId should work directly.
 
-    final soundsList = activeGame!.sounds;
+    final data = activeGame;
+    if (data == null) return;
+
+    final soundsList = data.sounds;
     if (sfxId < 0 || sfxId >= soundsList.length) return;
 
     final raw8bitBytes = soundsList[sfxId].bytes;