fix(apps): consolidate FormzInput validators and fix login screen

- Move FormzInput validators to core/form_inputs/form_inputs.dart
- Fix login_screen.dart syntax error (missing 'class' keyword)
- Remove unused _isLoading field
- Fix unnecessary const keywords
- Update login_cubit and register_cubit imports
- Remove duplicate FormzInput definitions from register_cubit
- Add Toast and Banner UI feedback system
- Remove legacy login/register screens (login_code, login_email, login_password, register_step2)
- Remove unused warning_banner widget
- Update tests for new error messages and DI setup

apps/lib/core/router/app_router.dart

@@ -2,11 +2,9 @@ import 'package:go_router/go_router.dart';
 import '../../features/auth/presentation/bloc/auth_bloc.dart';
 import '../../features/auth/presentation/bloc/auth_state.dart';
 import 'go_router_refresh_stream.dart';
-import '../../features/auth/ui/screens/login_email_screen.dart';
-import '../../features/auth/ui/screens/login_password_screen.dart';
-import '../../features/auth/ui/screens/login_code_screen.dart';
+import '../../features/auth/ui/screens/login_screen.dart';
 import '../../features/auth/ui/screens/register_screen.dart';
-import '../../features/auth/ui/screens/register_step2_screen.dart';
+import '../../features/auth/ui/screens/register_verification_screen.dart';
 import '../../features/home/ui/screens/home_screen.dart';
 import '../../features/messages/ui/screens/message_invite_list_screen.dart';
 import '../../features/messages/ui/screens/message_invite_detail_screen.dart';
@@ -60,22 +58,14 @@ GoRouter createAppRouter(AuthBloc authBloc) {
       return null;
     },
     routes: [
-      GoRoute(path: '/', builder: (context, state) => const LoginEmailScreen()),
-      GoRoute(
-        path: '/login/password',
-        builder: (context, state) => const LoginPasswordScreen(),
-      ),
-      GoRoute(
-        path: '/login/code',
-        builder: (context, state) => const LoginCodeScreen(),
-      ),
+      GoRoute(path: '/', builder: (context, state) => const LoginScreen()),
       GoRoute(
         path: '/register',
         builder: (context, state) => const RegisterScreen(),
       ),
       GoRoute(
-        path: '/register/step2',
-        builder: (context, state) => const RegisterStep2Screen(),
+        path: '/register/verification',
+        builder: (context, state) => const RegisterVerificationScreen(),
       ),
       GoRoute(path: '/home', builder: (context, state) => const HomeScreen()),
       GoRoute(