fix: ensure redirect handling in LoginPage after user login

frontend/src/pages/LoginPage.tsx

@@ -15,9 +15,10 @@ function LoginPage() {
 
   useEffect(() => {
     if (!loading && user) {
-      navigate('/');
+      const redirect = searchParams.get('redirect');
+      navigate(redirect ? decodeURIComponent(redirect) : '/');
     }
-  }, [user, loading, navigate]);
+  }, [user, loading, navigate, searchParams]);
 
   const saveRedirectAndGo = (oauthUrl: string) => {
     const redirect = searchParams.get('redirect');
@@ -40,7 +41,8 @@ function LoginPage() {
       setGuestLoading(true);
       const token = await guestLogin();
       await login(token);
-      const redirect = searchParams.get('redirect');
+      const redirect = searchParams.get('redirect') || sessionStorage.getItem('oauth_redirect');
+      sessionStorage.removeItem('oauth_redirect');
       navigate(redirect ? decodeURIComponent(redirect) : '/');
     } catch (err) {
       console.error('Guest login failed:', err);