refactor: 移除技能卡牌系统相关代码和资源

1. 删除MSkillBoxComp组件文件及对应的meta配置
2. 从UI配置中移除SkillBox相关注册项
3. 删除MSkillBox.prefab及其meta配置
4. 新增winbox和winboxbg弹窗预制体资源
5. 优化CardLiteComp的注释描述

assets/resources/gui/element/winboxbg.prefab.meta

@@ -0,0 +1,13 @@
+{
+  "ver": "1.1.50",
+  "importer": "prefab",
+  "imported": true,
+  "uuid": "fa3905e2-e4b8-4b97-8133-f6012983b023",
+  "files": [
+    ".json"
+  ],
+  "subMetas": {},
+  "userData": {
+    "syncNodeName": "winboxbg"
+  }
+}