重构布局组件，优化导航栏和头部结构；调整样式以改善响应式设计

src/app/admin/layout.tsx

@@ -1,7 +1,7 @@
 import {ReactNode} from 'react'
-import {merge} from '@/lib/utils'
 import Header from './_client/header'
-import Navbar from '@/app/admin/_client/navbar'
+import Navbar from './_client/navbar'
+import Layout from './_client/layout'
 
 export type AdminLayoutProps = {
   children: ReactNode
@@ -9,17 +9,10 @@ export type AdminLayoutProps = {
 
 export default async function AdminLayout(props: AdminLayoutProps) {
   return (
-    <div className={merge(
-      `h-screen bg-card overflow-hidden min-w-7xl overflow-y-hidden`,
-      `flex items-stretch`,
-    )}>
-
-      <Navbar/>
-
-      <div className="flex-auto flex flex-col items-stretch">
-        <Header/>
-        {props.children}
-      </div>
-    </div>
+    <Layout
+      navbar={<Navbar/>}
+      header={<Header/>}
+      content={props.children}
+    />
   )
 }