refactor(资源管理): 集中资源加载逻辑到ComponentManager

将分散在各处的资源加载逻辑统一到ComponentManager中管理
添加对UI组件、主题、物品纹理和饲料的集中管理
移除SkillIconBase.tscn并迁移到UI目录

scripts/Statemachine/ItemDropped.gd

@@ -50,7 +50,7 @@ static func generate(
 		spawnPosition: Vector2,
 		addToWorld: bool = true
 	):
-	var instance: ItemDropped = load("res://components/UI/ItemDropped.tscn").instantiate()
+	var instance: ItemDropped = ComponentManager.getUIComponent("ItemDropped").instantiate()
 	instance.item = itemType
 	instance.stackCount = count
 	instance.position = spawnPosition