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/demos/index.ts

@@ -0,0 +1 @@
+export * from './status';

playground/src/api/demos/status.ts

@@ -0,0 +1,10 @@
+import { requestClient } from '#/api/request';
+
+/**
+ * 模拟任意状态码
+ */
+async function getMockStatusApi(status: string) {
+  return requestClient.get('/status', { params: { status } });
+}
+
+export { getMockStatusApi };