Constant SIDEBAR_PRELOAD_SCRIPT 

const SIDEBAR_PRELOAD_SCRIPT: &str = r#"
(function() {
    try {
        var html = document.documentElement;
        var width = parseFloat(localStorage.getItem('yggdrasil-admin-sidebar-width'));
        if (width >= 200 && width <= 320) html.style.setProperty('--admin-sidebar-w', width + 'px');
        if (localStorage.getItem('yggdrasil-admin-sidebar-collapsed') === 'true') {
            html.setAttribute('data-admin-sidebar', 'collapsed');
        }
    } catch (e) {}
})();
"#;

首屏恢复侧栏宽度与折叠状态，避免 WASM 接管前侧栏跳一下。外壳挂载后改由 根元素的 data-sidebar 与 --admin-sidebar-w 决定。