feat(l10n): add demo email and code hints for localization

Author: fulleni

lib/l10n/app_localizations.dart

@@ -1417,6 +1417,18 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'Disabled'**
   String get appStatusDisabled;
+
+  /// Hint text shown in demo environment for the login email.
+  ///
+  /// In en, this message translates to:
+  /// **'For demo, use email: {email}'**
+  String demoEmailHint(String email);
+
+  /// Hint text shown in demo environment for the verification code.
+  ///
+  /// In en, this message translates to:
+  /// **'For demo, use code: {code}'**
+  String demoCodeHint(String code);
 }
 
 class _AppLocalizationsDelegate

lib/l10n/app_localizations_ar.dart

@@ -737,4 +737,14 @@ class AppLocalizationsAr extends AppLocalizations {
 
   @override
   String get appStatusDisabled => 'معطل';
+
+  @override
+  String demoEmailHint(String email) {
+    return 'للعرض التجريبي، استخدم البريد الإلكتروني: $email';
+  }
+
+  @override
+  String demoCodeHint(String code) {
+    return 'للعرض التجريبي، استخدم الرمز: $code';
+  }
 }

lib/l10n/app_localizations_en.dart

@@ -735,4 +735,14 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get appStatusDisabled => 'Disabled';
+
+  @override
+  String demoEmailHint(String email) {
+    return 'For demo, use email: $email';
+  }
+
+  @override
+  String demoCodeHint(String code) {
+    return 'For demo, use code: $code';
+  }
 }