feat(auth): 랜딩 시작 분기와 앱 라우트 가드를 추가

src/features/auth/components/AuthRedirectButton.tsx

@@ -0,0 +1,47 @@
+"use client";
+
+import type { ReactNode } from "react";
+import Cookies from "js-cookie";
+import { useRouter } from "next/navigation";
+import { TOKEN_COOKIE_KEY } from "@/features/auth/model/constants";
+import { Button, type ButtonSize, type ButtonVariant } from "@/shared/ui/Button";
+import { useAuthStore } from "@/store/useAuthStore";
+
+interface AuthRedirectButtonProps {
+  children: ReactNode;
+  className?: string;
+  size?: ButtonSize;
+  variant?: ButtonVariant;
+  authenticatedHref?: string;
+  unauthenticatedHref?: string;
+}
+
+export function AuthRedirectButton({
+  children,
+  className,
+  size = "md",
+  variant = "primary",
+  authenticatedHref = "/space",
+  unauthenticatedHref = "/login",
+}: AuthRedirectButtonProps) {
+  const router = useRouter();
+  const accessToken = useAuthStore((state) => state.accessToken);
+  const isAuthenticated = useAuthStore((state) => state.isAuthenticated);
+
+  const handleClick = () => {
+    const hasAccessToken = isAuthenticated || Boolean(accessToken) || Boolean(Cookies.get(TOKEN_COOKIE_KEY));
+    router.push(hasAccessToken ? authenticatedHref : unauthenticatedHref);
+  };
+
+  return (
+    <Button
+      type="button"
+      variant={variant}
+      size={size}
+      className={className}
+      onClick={handleClick}
+    >
+      {children}
+    </Button>
+  );
+}

src/features/auth/model/constants.ts

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+export const TOKEN_COOKIE_KEY = "vr_access_token";
+export const REFRESH_TOKEN_COOKIE_KEY = "vr_refresh_token";