[fix] 레이아웃 분리

Author: ahk0413

src/app/design-system/page.tsx renamed to src/app/(no-layout)/design-system/page.tsx

@@ -0,0 +1,4 @@
+function NoLayout({ children }: { children: React.ReactNode }) {
+  return <main className="flex flex-1">{children}</main>;
+}
+export default NoLayout;