Add audio bus configuration for various sound effects and update main scene reference

scripts/ui/credits.gd

@@ -0,0 +1,6 @@
+extends Control
+
+func _unhandled_input(event: InputEvent) -> void:
+	if event.is_action_pressed("ui_cancel"):
+		if UiManager.is_screen_on_top(self):
+			UiManager.pop_screen()