관리자 메인 화면 너비를 홈 화면에 맞춤

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/features/admin/AdminHome.jsx

@@ -67,7 +67,7 @@ export default function AdminHome() {
   })
 
   return (
-    <div className="space-y-8">
+    <div className="space-y-8 max-w-5xl mx-auto pt-6">
       {/* 메뉴 섹션 */}
       <section className="space-y-4">
         <div className="flex items-center justify-between">