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/features/auth/ui/screens/register_screen.dart

@@ -3,8 +3,10 @@ import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:formz/formz.dart';
 import 'package:go_router/go_router.dart';
 import '../../../../core/theme/design_tokens.dart';
+import '../../../../core/di/injection.dart';
 import '../../../../shared/widgets/app_button.dart';
-import '../../../../shared/widgets/warning_banner.dart';
+import '../../../../shared/widgets/banner/app_banner.dart';
+import '../../../../shared/widgets/toast/toast_type.dart';
 import '../../presentation/cubits/register_cubit.dart';
 import '../../data/auth_repository.dart';
 
@@ -14,7 +16,7 @@ class RegisterScreen extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return BlocProvider(
-      create: (context) => RegisterCubit(context.read<AuthRepository>()),
+      create: (context) => RegisterCubit(sl<AuthRepository>()),
       child: const RegisterView(),
     );
   }
@@ -53,7 +55,7 @@ class _RegisterViewState extends State<RegisterView> {
 
     final success = await cubit.submitStep1();
     if (success && mounted) {
-      context.push('/register/step2', extra: cubit);
+      context.push('/register/verification', extra: cubit);
     }
   }
 
@@ -146,9 +148,9 @@ class _RegisterViewState extends State<RegisterView> {
               if (state.errorMessage != null)
                 Padding(
                   padding: const EdgeInsets.only(top: 8),
-                  child: WarningBanner(
+                  child: AppBanner(
                     message: state.errorMessage!,
-                    visible: true,
+                    type: ToastType.error,
                   ),
                 ),
               const SizedBox(height: 12),