fix: 更新默认海报图URL以优化图片质量

 <!--
  * @Date: 2022-09-19 14:11:06
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-09-25 10:50:46
+ * @LastEditTime: 2025-09-26 10:45:08
  * @FilePath: /lls_program/src/pages/ActivitiesCover/index.vue
  * @Description: 活动海报页面 - 展示活动信息并处理定位授权
 -->
@@ -153,7 +153,7 @@ import { handleSharePageAuth, addShareFlag } from '@/utils/authRedirect'
 import { THEME_COLORS } from '@/utils/config';
 
 // 默认海报图
-const defaultPoster = 'https://cdn.ipadbiz.cn/lls_prog/images/welcome_8.jpg';
+const defaultPoster = 'https://cdn.ipadbiz.cn/lls_prog/images/welcome_8.jpg?imageMogr2/strip/quality/60';
 
 // 系统信息
 const systemInfo = ref({});