0.2.5 feat: WebView 启动等待页 / WebView Startup Loading Page

WebView 版本新增 ChemSSH 启动等待页，服务启动期间代理自动重试并显示加载提示，就绪后无缝过渡，不再出现 502 错误需要手动刷新的情况。
Added a startup loading page for WebView mode. The proxy now automatically retries when ChemSSH is still initializing and shows a loading indicator. Once the service is ready, the page transitions seamlessly — no more 502 errors requiring manual refresh.