Add auth session flow and sign-in UX

test/features/auth/session_controller_test.dart

@@ -0,0 +1,59 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:relationship_saver/core/auth/in_memory_token_store.dart';
+import 'package:relationship_saver/features/auth/session_controller.dart';
+import 'package:relationship_saver/integrations/backend/backend_gateway_fake.dart';
+import 'package:relationship_saver/integrations/backend/backend_gateway_provider.dart';
+import 'package:relationship_saver/integrations/backend/models/backend_models.dart';
+
+void main() {
+  test('initial state is signed out when token store is empty', () async {
+    final ProviderContainer container = ProviderContainer(
+      overrides: [
+        tokenStoreProvider.overrideWithValue(InMemoryTokenStore()),
+        backendGatewayProvider.overrideWithValue(BackendGatewayFake()),
+      ],
+    );
+    addTearDown(container.dispose);
+
+    final AuthSession? session = await container.read(
+      sessionControllerProvider.future,
+    );
+    expect(session, isNull);
+  });
+
+  test('sign-in creates session and sign-out clears it', () async {
+    final InMemoryTokenStore tokenStore = InMemoryTokenStore();
+    final ProviderContainer container = ProviderContainer(
+      overrides: [
+        tokenStoreProvider.overrideWithValue(tokenStore),
+        backendGatewayProvider.overrideWithValue(BackendGatewayFake()),
+      ],
+    );
+    addTearDown(container.dispose);
+
+    await container
+        .read(sessionControllerProvider.notifier)
+        .signIn(
+          method: SignInMethod.password,
+          email: 'demo@example.com',
+          password: 'password123',
+        );
+
+    final AuthSession? signedIn = container
+        .read(sessionControllerProvider)
+        .asData
+        ?.value;
+    expect(signedIn, isNotNull);
+    expect(signedIn?.user.email, 'demo@example.com');
+
+    await container.read(sessionControllerProvider.notifier).signOut();
+
+    final AuthSession? signedOut = container
+        .read(sessionControllerProvider)
+        .asData
+        ?.value;
+    expect(signedOut, isNull);
+    expect(await tokenStore.read(), isNull);
+  });
+}

test/widget_test.dart

@@ -1,5 +1,7 @@
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:relationship_saver/core/auth/in_memory_token_store.dart';
+import 'package:relationship_saver/integrations/backend/backend_gateway_provider.dart';
 import 'package:relationship_saver/main.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
@@ -8,11 +10,16 @@ void main() {
     SharedPreferences.setMockInitialValues(<String, Object>{});
   });
 
-  testWidgets('renders dashboard flow', (WidgetTester tester) async {
-    await tester.pumpWidget(const ProviderScope(child: RelationshipSaverApp()));
+  testWidgets('renders sign-in flow by default', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      ProviderScope(
+        overrides: [tokenStoreProvider.overrideWithValue(InMemoryTokenStore())],
+        child: const RelationshipSaverApp(),
+      ),
+    );
     await tester.pumpAndSettle();
 
-    expect(find.text('Today'), findsOneWidget);
-    expect(find.text('Active People'), findsOneWidget);
+    expect(find.text('Sign in to continue'), findsOneWidget);
+    expect(find.text('Sign In'), findsOneWidget);
   });
 }