feat(l10n): add demo email suggestion message in Arabic and English

- Add new localization key 'demoEmailSuggestionMessage' for demo mode email suggestion
- Implement message in both Arabic and English localization files
- Maintain existing translations and add appropriate descriptions for new messages

Author: fulleni

lib/l10n/app_localizations.dart

@@ -1550,6 +1550,12 @@ abstract class AppLocalizations {
   /// **'Demo Mode: Use code {code}'**
   String demoVerificationCodeMessage(String code);
 
+  /// Message shown in demo mode to suggest an email for sign-in
+  ///
+  /// In en, this message translates to:
+  /// **'Demo Mode: Use email {email}'**
+  String demoEmailSuggestionMessage(String email);
+
   /// Label for Headline content type
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_ar.dart

@@ -804,6 +804,11 @@ class AppLocalizationsAr extends AppLocalizations {
     return 'وضع العرض التوضيحي: استخدم الرمز $code';
   }
 
+  @override
+  String demoEmailSuggestionMessage(String email) {
+    return 'وضع العرض التوضيحي: استخدم البريد الإلكتروني $email';
+  }
+
   @override
   String get contentTypeHeadline => 'العناوين الرئيسية';
 

lib/l10n/app_localizations_en.dart

@@ -807,6 +807,11 @@ class AppLocalizationsEn extends AppLocalizations {
     return 'Demo Mode: Use code $code';
   }
 
+  @override
+  String demoEmailSuggestionMessage(String email) {
+    return 'Demo Mode: Use email $email';
+  }
+
   @override
   String get contentTypeHeadline => 'Headlines';
 

lib/l10n/arb/app_ar.arb

@@ -1046,6 +1046,16 @@
             }
         }
     },
+    "demoEmailSuggestionMessage": "وضع العرض التوضيحي: استخدم البريد الإلكتروني {email}",
+    "@demoEmailSuggestionMessage": {
+        "description": "رسالة تظهر في وضع العرض التوضيحي لاقتراح بريد إلكتروني لتسجيل الدخول",
+        "placeholders": {
+            "email": {
+                "type": "String",
+                "example": "demo@example.com"
+            }
+        }
+    },
     "contentTypeHeadline": "العناوين الرئيسية",
     "@contentTypeHeadline": {
         "description": "Label for Headline content type"

lib/l10n/arb/app_en.arb

@@ -602,7 +602,6 @@
     "@headlinesFeedFilterNoSourcesMatch": {
         "description": "Message shown when no sources match the selected filters"
     },
-
     "searchModelTypeHeadline": "Headlines",
     "@searchModelTypeHeadline": {
         "description": "Dropdown display name for Headline search type"
@@ -639,7 +638,6 @@
     "@searchHintTextCountry": {
         "description": "Hint text for searching countries"
     },
-
     "searchPageInitialHeadline": "Start Your Search",
     "@searchPageInitialHeadline": {
         "description": "Generic headline for the initial state of the search page"
@@ -1038,7 +1036,7 @@
     "@followedCategoriesEmptySubheadline": {
         "description": "Subheadline for empty state on followed categories page"
     },
-     "demoVerificationCodeMessage": "Demo Mode: Use code {code}",
+    "demoVerificationCodeMessage": "Demo Mode: Use code {code}",
     "@demoVerificationCodeMessage": {
         "description": "Message shown in demo mode to provide the verification code",
         "placeholders": {
@@ -1048,6 +1046,16 @@
             }
         }
     },
+    "demoEmailSuggestionMessage": "Demo Mode: Use email {email}",
+    "@demoEmailSuggestionMessage": {
+        "description": "Message shown in demo mode to suggest an email for sign-in",
+        "placeholders": {
+            "email": {
+                "type": "String",
+                "example": "demo@example.com"
+            }
+        }
+    },
     "contentTypeHeadline": "Headlines",
     "@contentTypeHeadline": {
         "description": "Label for Headline content type"
@@ -1117,4 +1125,4 @@
     "@unfollowButtonText": {
         "description": "Text for the unfollow button on suggestion items"
     }
-}
+}