master volume settings

common/game_data/scripts/settings_data.gd

@@ -30,6 +30,11 @@ const AVAILABLE_LANGUAGES_LABEL = [
 
 #region ------------------ Sound ------------------
 
+@export var master_volume : float = 1.0 :
+    set(v):
+        master_volume = v
+        sound_changed.emit(self)
+
 @export var music_volume : float = 0.7 :
     set(v):
         music_volume = v