refactor: replace Toast with Sonner

frontend/app/routes/platform.tsx

@@ -7,7 +7,6 @@ import type { ActivePage, NavigationItem, SubPage } from "./platform.navigation"
 import { Collapsible } from "@base-ui/react/collapsible";
 
 import type { Route } from "./+types/platform";
-import { Toast } from "../components/common/Toast";
 import { Topbar } from "../components/common/Topbar";
 import Icon from "../components/common/Icon";
 import {
@@ -165,8 +164,6 @@ function AuthenticatedLayout() {
   const endEditing = useScriptWorkspaceStore((s) => s.endEditing);
   const selectScript = useScriptWorkspaceStore((s) => s.selectScript);
 
-  const toast = useUiStore((s) => s.toast);
-  const dismissToast = useUiStore((s) => s.dismissToast);
   const workspaceMenuOpen = useUiStore((s) => s.workspaceMenuOpen);
   const setWorkspaceMenuOpen = useUiStore((s) => s.setWorkspaceMenuOpen);
 
@@ -199,13 +196,6 @@ function AuthenticatedLayout() {
   // 心跳 / cleanup / 切页结束编辑 / 卸载前释放
   useEditSessionLifecycle({ activePage });
 
-  // toast 自动消失
-  useEffect(() => {
-    if (!toast) return;
-    const timer = window.setTimeout(dismissToast, 3200);
-    return () => window.clearTimeout(timer);
-  }, [toast, dismissToast]);
-
   // 原 common/Sidebar 的编辑会话守卫上移到这里：切出 /scripts 时有活动编辑
   // 会话先 endEditing，回工作台时清空选中脚本；再按当前激活页导航。
   function guardedNavigate(page: ActivePage, sub?: SubPage) {
@@ -279,7 +269,6 @@ function AuthenticatedLayout() {
         <Outlet />
       </SidebarInset>
 
-      <Toast toast={toast} />
     </SidebarProvider>
   );
 }