basic login fix

lib/pages/landing_page.dart

@@ -0,0 +1,37 @@
+import 'package:briessenchecker/pages/dashboard_page.dart';
+import 'package:flutter/material.dart';
+import 'package:supabase_flutter/supabase_flutter.dart';
+
+import '../services/dbhelper.dart';
+import 'login_page.dart';
+
+class LandingPage extends StatefulWidget {
+  const LandingPage({super.key});
+  static const routeName = '/';
+
+  @override
+  State<LandingPage> createState() => _LandingPageState();
+}
+
+class _LandingPageState extends State<LandingPage> {
+  bool _isLoggedIn = false;
+  @override
+  void initState() {
+    DbHelper.authChangeEventStream.listen(_onAuthEvent);
+    super.initState();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    if (_isLoggedIn) return const DashboardPage();
+    return const LoginPage();
+  }
+
+  void _onAuthEvent(AuthState event) {
+    if (event.event == AuthChangeEvent.signedIn) {
+      setState(() => _isLoggedIn = true);
+    } else if (event.event == AuthChangeEvent.signedOut) {
+      setState(() => _isLoggedIn = false);
+    }
+  }
+}