feat: 添加敌人并且追踪player，同时避免敌人重叠

resources/units/unit_stats.gd

@@ -0,0 +1,19 @@
+extends Resource
+class_name UnitStats
+
+enum UnitType {
+	PLAYER,
+	ENEMY
+}
+
+@export var name: String
+@export var type: UnitType
+@export var icon: Texture2D
+@export var health := 1
+@export var health_increase_per_wave := 1.0
+@export var damage := 1.0
+@export var damage_increase_per_wave := 1.0
+@export var speed := 300
+@export var luck := 1.0
+@export var block_chance := 0.0
+@export var gold_drop := 1