feat(ui): unify content shell layout

app/(account)/layout.tsx

@@ -4,13 +4,13 @@ import { Header } from "@/components/header"
 
 export default function AccountLayout({ children }: { children: React.ReactNode }) {
   return (
-    <div className="flex min-h-screen flex-col">
+    <div className="flex min-h-screen flex-col bg-muted/20">
       <Header />
-      <div className="container mx-auto flex flex-1 px-4">
+      <div className="mx-auto flex w-full max-w-5xl flex-1 px-4">
         <div className="hidden md:block">
           <AccountSidebar />
         </div>
-        <main className="flex-1 p-6">
+        <main className="flex-1 py-8 md:px-6">
           <AuthGuard>{children}</AuthGuard>
         </main>
       </div>

app/(account)/notifications/page.tsx

@@ -223,7 +223,7 @@ export default function NotificationsPage() {
   )
 
   return (
-    <div className="container mx-auto max-w-2xl px-4 py-8 space-y-6">
+    <div className="mx-auto max-w-2xl space-y-6">
       <div className="flex items-center justify-between pb-2 border-b border-border/40">
         <div className="flex items-center gap-3">
           <h1 className="text-2xl font-bold tracking-tight">通知中心</h1>

app/(account)/settings/page.tsx

@@ -94,7 +94,7 @@ export default function SettingsPage() {
   }
 
   return (
-    <div className="container mx-auto max-w-2xl px-4 py-8 space-y-6">
+    <div className="mx-auto max-w-2xl space-y-6">
       <h1 className="text-2xl font-bold">个人设置</h1>
 
       <Card>

app/(account)/verify/page.tsx

@@ -156,7 +156,7 @@ export default function VerifyPage() {
   }
 
   return (
-    <div className="container mx-auto max-w-2xl px-4 py-8 space-y-8">
+    <div className="mx-auto max-w-2xl space-y-8">
       <h1 className="text-2xl font-bold">身份认证</h1>
 
       <section className="space-y-4">

app/(account)/wallet/page.tsx

@@ -202,7 +202,7 @@ export default function WalletPage() {
   }
 
   return (
-    <div className="container mx-auto max-w-2xl px-4 py-8 space-y-6">
+    <div className="mx-auto max-w-2xl space-y-6">
       <h1 className="text-2xl font-bold">钱包</h1>
 
       <Card className="border-border/60 shadow-sm">