new battery model with shaders

Scripts/build_manager.gd

@@ -2,6 +2,7 @@ extends Node
 
 @onready var DoubleBeds = preload("res://Scenes/Prefabs/DoubleBeds.tscn")
 @onready var Pot = preload("res://Scenes/Prefabs/Pot.tscn")
+@onready var Battery = preload("res://Scenes/Prefabs/Battery.tscn")
 
 signal build_object_selected
 
@@ -23,6 +24,8 @@ func get_preview_object():
 			selected_object = DoubleBeds
 		1:
 			selected_object = Pot
+		2:
+			selected_object = Battery
 	return selected_object