refactor: migrate demo applications to playground (#4116)

* chore: detail adjustment

* refactor: Migrate demo applications to playground

* perf: logic optimization

* chore: update docs

* chore: update docs

playground/src/api/core/user.ts

@@ -0,0 +1,10 @@
+import type { UserInfo } from '@vben/types';
+
+import { requestClient } from '#/api/request';
+
+/**
+ * 获取用户信息
+ */
+export async function getUserInfoApi() {
+  return requestClient.get<UserInfo>('/user/info');
+}