feat(ItemShow): 为物品展示添加自动释放功能

在ItemShow.generate方法中新增isAutoFree参数，控制物品展示节点是否自动释放。这解决了需要手动管理物品展示节点内存的问题。

scripts/Statemachine/EntityBase.gd

@@ -84,7 +84,7 @@ func _ready():
 		)
 		itemCollected.connect(
 			func(itemType, amount):
-				UIState.itemCollect.add_child(ItemShow.generate(itemType, amount))
+				UIState.itemCollect.add_child(ItemShow.generate(itemType, amount, true))
 		)
 	else:
 		currentFocusedBoss = get_tree().get_nodes_in_group("players")[0]

scripts/Statemachine/ItemShow.gd

@@ -19,8 +19,9 @@ func _physics_process(_delta):
 	avatarTexture.texture = ItemStore.getTexture(type)
 	countLabel.text = str(count)
 
-static func generate(itemType: ItemStore.ItemType, itemCount: int = 1):
+static func generate(itemType: ItemStore.ItemType, itemCount: int = 1, isAutoFree: bool = false):
 	var item = preload("res://components/UI/ItemShow.tscn").instantiate()
 	item.type = itemType
 	item.count = itemCount
+	item.autoFree = isAutoFree
 	return item