fix: prevent logged-in users from accessing login/signup pages

frontend/src/App.jsx

@@ -15,15 +15,16 @@ import Layout from './components/Layout';
 import ProtectedRoute from './components/ProtectedRoute';
 import SetupProtectedRoute from './components/SetupProtectedRoute';
 import RecurringTransactions from './pages/RecurringTransactions';
+import { PublicRoute } from './components/PublicRoute';
 
 function App() {
   return (
     <>
       <Routes>
         {/* Public Routes */}
         <Route path="/" element={<WelcomePage />} />
-        <Route path="/login" element={<LoginPage />} />
-        <Route path="/register" element={<RegisterPage />} />
+        <Route path="/login" element={<PublicRoute><LoginPage /></PublicRoute>} />
+        <Route path="/register" element={<PublicRoute><RegisterPage /></PublicRoute>} />
         <Route path="/contact" element={<ContactUs />} />
         {/* Protected Routes */}
         <Route
@@ -42,7 +43,7 @@ function App() {
             </SetupProtectedRoute>
           }
         >
-          <Route path="/dashboard" element={<DashboardPage />} />
+          <Route path="/dashboard" element={<ProtectedRoute><DashboardPage /></ProtectedRoute>} />
           <Route path="/transactions" element={<TransactionsPage />} />
           <Route path="/receipts" element={<ReceiptsPage />} />
           <Route path="/settings" element={<SettingsPage />} />

frontend/src/components/PublicRoute.jsx

@@ -0,0 +1,24 @@
+import React from 'react';
+import { Navigate } from 'react-router-dom';
+import useAuth from '../hooks/useAuth';
+import Spinner from './Spinner';
+
+const PublicRoute = ({ children }) => {
+  const { user, loading } = useAuth();
+
+  if (loading) {
+    return (
+      <div className="flex justify-center items-center min-h-screen">
+        <Spinner />
+      </div>
+    );
+  }
+
+  if (user) {
+    return <Navigate to="/dashboard" replace />;
+  }
+
+  return children;
+};
+
+export default PublicRoute;