add animations and train selector logic

core/game_menu/arrow_button.gd

@@ -1,6 +1,10 @@
 @tool
 extends Control
 
+class_name ArrowButton
+
+signal on_pressed
+
 @export var image: Texture:
 	set(value):
 		image = value
@@ -19,3 +23,7 @@ func _ready():
 		$%Texture.texture = image
 		$%Texture.flip_h = flip_h
 		
+
+func _on_gui_input(event: InputEvent) -> void:
+	if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT and event.pressed:
+		on_pressed.emit()