feat(authentication): add demo email suggestion for request code page

- Add conditional rendering of demo email suggestion based on app environment
- Use BlocSelector to listen for AppEnvironment state
- Display suggestion only in demo environment
- Apply styling for better visibility

Author: fulleni

lib/authentication/view/request_code_page.dart

@@ -5,6 +5,8 @@ import 'dart:async';
 
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:flutter_news_app_mobile_client_full_source_code/app/bloc/app_bloc.dart';
+import 'package:flutter_news_app_mobile_client_full_source_code/app/config/config.dart';
 import 'package:flutter_news_app_mobile_client_full_source_code/authentication/bloc/authentication_bloc.dart';
 import 'package:flutter_news_app_mobile_client_full_source_code/l10n/l10n.dart';
 import 'package:flutter_news_app_mobile_client_full_source_code/router/routes.dart';
@@ -130,6 +132,30 @@ class _RequestCodeView extends StatelessWidget {
                         ),
                         textAlign: TextAlign.center,
                       ),
+                      // Display demo email suggestion if in demo environment
+                      BlocSelector<AppBloc, AppState, AppEnvironment?>(
+                        selector: (state) => state.environment,
+                        builder: (context, environment) {
+                          if (environment == AppEnvironment.demo) {
+                            return Column(
+                              children: [
+                                const SizedBox(height: AppSpacing.md),
+                                Text(
+                                  l10n.demoEmailSuggestionMessage(
+                                    'admin@mail.com',
+                                  ),
+                                  style: textTheme.bodyMedium?.copyWith(
+                                    color: colorScheme.secondary,
+                                    fontWeight: FontWeight.bold,
+                                  ),
+                                  textAlign: TextAlign.center,
+                                ),
+                              ],
+                            );
+                          }
+                          return const SizedBox.shrink();
+                        },
+                      ),
                       const SizedBox(height: AppSpacing.xxl),
                       _EmailLinkForm(isLoading: isLoading),
                     ],