feat: 增加下载、购买记录接口

module/song_singledownlist.js

@@ -0,0 +1,16 @@
+// 已购买单曲
+
+const createOption = require('../util/option.js')
+module.exports = (query, request) => {
+  const data = {
+    limit: query.limit || '20',
+    offset: query.offset || '0',
+    total: 'true',
+  }
+  return request(
+    'POST',
+    `/api/member/song/singledownlist`,
+    data,
+    createOption(query),
+  )
+}