feat: 添加敌人并且追踪player，同时避免敌人重叠

scenes/arena/camera_2d.gd

@@ -0,0 +1,13 @@
+extends Camera2D
+class_name Camera
+
+# Called when the node enters the scene tree for the first time.
+func _ready() -> void:
+	pass # Replace with function body.
+
+
+# Called every frame. 'delta' is the elapsed time since the previous frame.
+func _process(delta: float) -> void:
+	if is_instance_valid(Global.player):
+		global_position = Global.player.position
+	pass