实现赛程表导出功能

- 添加 exportSchedule API 调用后端导出接口
- 实现 handleExport 方法，支持下载 Excel 文件
- 文件名格式：赛程表_赛事名称.xlsx

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/api/martial/activitySchedule.js

@@ -183,3 +183,16 @@ export const saveDispatch = (data) => {
     data
   })
 }
+
+/**
+ * 导出赛程表
+ * @param {Number} competitionId - 赛事ID
+ */
+export const exportSchedule = (competitionId) => {
+  return request({
+    url: '/martial/export/schedule',
+    method: 'get',
+    params: { competitionId },
+    responseType: 'blob'
+  })
+}