style(marketing-activity): 调整样式导入方式以提升可维护性

src/views/marketing-activity/index.vue

@@ -326,5 +326,6 @@ export default {
 }
 </script>
 
-<style lang="scss" scoped src="./index.scss">
+<style lang="scss" scoped >
+@import './index.scss'
 </style>