📝 docs(layout): remove duplicate Toaster component in MainLayout

- 删除MainLayout中重复的Toaster组件，避免页面中出现多个提示框实例

src/client/admin-shadcn/layouts/MainLayout.tsx

@@ -146,8 +146,6 @@ export const MainLayout = () => {
 
   return (
     <div className="flex h-screen bg-background">
-      <Toaster />
-      
       {/* Desktop Sidebar */}
       <aside className={cn(
         "hidden md:block border-r bg-background transition-all duration-200",