fix(CSS): 修复UI组件CSS类为空的问题

- 库模式默认JS与CSS独立，引入插件合并
- 修改variables文件名为_variables
- 删除所有scoped，更遵循库开发规范

BREAKING CHANGES: 2.0.0->2.1.0

package.json

@@ -46,7 +46,8 @@
     "@typescript-eslint/eslint-plugin": "^8.46.4",
     "@typescript-eslint/parser": "^8.46.4",
     "@vue/eslint-config-typescript": "^14.1.0",
-    "eslint-plugin-vue": "^9.33.0"
+    "eslint-plugin-vue": "^9.33.0",
+    "vite-plugin-css-injected-by-js": "^3.0.0"
   },
   "peerDependencies": {
     "vue": "^3.5.0",