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/Tools/QuickUI.gd

@@ -3,7 +3,7 @@ class_name QuickUI
 static func smallText(text: String, center: bool = true):
 	var label = Label.new()
 	label.text = text
-	label.theme = load("res://themes/smallText.tres")
+	label.theme = ComponentManager.getTheme("smallText")
 	if center:
 		label.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
 	return label
@@ -15,4 +15,4 @@ static func graySmallText(text: String, center: bool = true):
 	label.label_settings.font_color = Color(0.6, 0.6, 0.6, 1)
 	if center:
 		label.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
-	return label
+	return label