user interface在4月23日之前，都有switch to legacy ui按钮的，后续的是漏掉，还是取消了？

### 需求 / Requirement 请保留这个功能，因为这是我发现切换2个rust内核最简单的方法，现在没有此功能后，内核切换不了了。 ### 建议实现 / Suggested implements 建议继续保留此switch to legacy ui功能！新版本升级后，找不到切换传统界面，不管怎么弄都无法用rust内核啦，反而不适应啦，请恢复这个功能。我还是回到4月23日前的版本。这个连续1个礼拜的更新，对于我来说，基本是个寂寞。 ### 备注 / Addition details <img width="806" height="638" alt="Image" src="https://github.com/user-attachments/assets/46fa10fd-b10b-45f7-ab7d-84f35389a35d" /> <img width="794" height="637" alt="Image" src="https://github.com/user-attachments/assets/e796b0d9-e7d2-4951-b495-1cabad377403" /> ### Clash Nyanpasu 版本号 / Clash Nyanpasu 2.0.0 ### 是否为 Pre-release / Is pre-release version 2f73450 ### 自查步骤 / Verify steps - [x] 如果您有足够的时间和能力，并愿意为此提交 PR，请勾上此复选框 / Pull request is welcome. Check this if you want to start a pull request - [x] 您已仔细查看并知情 [Q&A](https://nyanpasu.org/zh-cn/others/issues) 中的内容 / You have checked [Q&A](https://nyanpasu.org/others/issues) carefully - [x] 您已搜索过 [Issue Tracker](https://github.com/libnyanpasu/clash-nyanpasu/issues)，没有找到类似内容 / I have searched on [Issue Tracker](https://github.com/libnyanpasu/clash-nyanpasu/issues), No duplicate or related open issue has been found - [x] 您确保这个 Issue 只提及一个功能。如果您有多个功能请求，烦请发起多个 Issue / Ensure there is only one feature request in this issue. Please make multiply issue for multiply feature request - [x] 您确保已使用最新 Pre-release 版本测试，并且该功能在最新 Pre-release 版本中并未实现 / This feature have not implemented in latest Pre-release version