add death sound and refactor jump sound

scripts/killzone.gd

@@ -1,9 +1,11 @@
 extends Area2D
 
 @onready var timer: Timer = $Timer
+@onready var death: AudioStreamPlayer2D = $Death
 
 func _on_body_entered(player_body: Node2D) -> void:
 	print("You died.")
+	death.play()
 	Engine.time_scale = 0.5
 	player_body.get_node(NodeTypes.COLLISION_SHAPE_2D).queue_free()
 	var player_character_body = player_body as CharacterBody2D