Feat: 로그인 여부에 따른 메인페이지 이동 및 dashboard 처리

app/(auth)/signup/page.tsx

@@ -1,4 +1,5 @@
 import Link from "next/link";
+import { AUTH_ROUTES } from "@/features/auth/constants";
 import FormMessage from "@/components/form-message";
 import SignupForm from "@/features/auth/components/signup-form";
 import {
@@ -42,7 +43,7 @@ export default async function SignupPage({
           <p className="text-center text-sm text-gray-600 dark:text-gray-400">
             이미 계정이 있으신가요?{" "}
             <Link
-              href="/login"
+              href={AUTH_ROUTES.LOGIN}
               className="font-semibold text-gray-900 transition-colors hover:text-black dark:text-gray-100 dark:hover:text-white"
             >
               로그인 하러 가기