官网示例 Spec 模式支持编辑

### AntV Open Source Contribution Plan（可选）

- [X] 我同意将这个 Issue 参与 OSCP 计划

### Issue 类型

中级任务

### 任务介绍

切换到 Spec 模式时支持编辑 Spec 并实时生效。


### 参考说明

_No response_

Start by locating the official website example and its Spec mode entry point, then run the example to understand the current mode switch. The work is complete when Spec can be edited in the example and changes take effect in real time; the issue names no files or tests.

Written by the indexing model from the issue text.