clean up file structure

world/building/building.gd

@@ -0,0 +1,15 @@
+class_name Building
+extends CollisionObject3D
+
+func _ready() -> void:
+	scale.y = randf_range(.5, 1.25)
+
+func hit(_proj: PlayerProjectile) -> void:
+	print("boom!")
+	SignalBus.building_destroyed.emit(self)
+	collision_layer = 1 # World collision only
+
+	%Mesh.hide()
+	%DestroyedMesh.show()
+	%GPUParticles3D.preprocess = randf()
+