feat(io): GameIO music seams; push room track per turn, silence at menu

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Semesterprojekt/src/main/java/thb/jeanluc/adventure/App.java

@@ -143,5 +143,6 @@ public final class App {
         new LookCommand().execute(ctx, List.of());
 
         game.run();
+        io.setMusic(null); // fade music out when returning to the menu
     }
 }

Semesterprojekt/src/main/java/thb/jeanluc/adventure/game/Game.java

@@ -109,6 +109,7 @@ public class Game {
                 ctx.getPlayer().getCurrentRoom());
         ctx.getIo().setMap(map);
         ctx.getIo().setQuests(QuestEngine.viewOf(ctx));
+        ctx.getIo().setMusic(ctx.getPlayer().getCurrentRoom().getMusic());
     }
 
     /**

Semesterprojekt/src/main/java/thb/jeanluc/adventure/io/GameIO.java

@@ -65,6 +65,16 @@ public interface GameIO {
         // no-op
     }
 
+    /** Per-turn current-room music track; null/blank = silence. Console no-op; GUI plays. */
+    default void setMusic(String track) {
+        // no audio in text mode
+    }
+
+    /** Applies the music volume/level. Console no-op; GUI sets it. */
+    default void setMusicLevel(MusicLevel level) {
+        // no audio in text mode
+    }
+
     /** On-demand quest log (the 'quests' command). Default renders styled text. */
     default void showQuests(QuestView view) {
         print(QuestText.render(view));