feat(localization): add translations for in-article ads settings

- Add Arabic and English translations for new checkbox label related to in-article ads
- Introduce placeholder for user role in both Arabic and English versions

Author: fulleni

lib/l10n/app_localizations.dart

@@ -2587,6 +2587,12 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'Publish Source'**
   String get publishSource;
+
+  /// Label for a checkbox to enable/disable in-article ads for a specific user role.
+  ///
+  /// In en, this message translates to:
+  /// **'Enable In-Article Ads for {role}'**
+  String enableInArticleAdsForRoleLabel(String role);
 }
 
 class _AppLocalizationsDelegate

lib/l10n/app_localizations_ar.dart

@@ -1382,4 +1382,9 @@ class AppLocalizationsAr extends AppLocalizations {
 
   @override
   String get publishSource => 'نشر المصدر';
+
+  @override
+  String enableInArticleAdsForRoleLabel(String role) {
+    return 'تمكين الإعلانات داخل المقال لـ $role';
+  }
 }

lib/l10n/app_localizations_en.dart

@@ -1387,4 +1387,9 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get publishSource => 'Publish Source';
+
+  @override
+  String enableInArticleAdsForRoleLabel(String role) {
+    return 'Enable In-Article Ads for $role';
+  }
 }

lib/l10n/arb/app_ar.arb

@@ -1745,5 +1745,15 @@
   "publishSource": "نشر المصدر",
   "@publishSource": {
     "description": "تلميح زر نشر المصدر."
+  },
+  "enableInArticleAdsForRoleLabel": "تمكين الإعلانات داخل المقال لـ {role}",
+  "@enableInArticleAdsForRoleLabel": {
+    "description": "Label for a checkbox to enable/disable in-article ads for a specific user role.",
+    "placeholders": {
+      "role": {
+        "type": "String",
+        "example": "مستخدم ضيف"
+      }
+    }
   }
 }

lib/l10n/arb/app_en.arb

@@ -1741,5 +1741,15 @@
   "publishSource": "Publish Source",
   "@publishSource": {
     "description": "Tooltip for the publish source button."
+  },
+  "enableInArticleAdsForRoleLabel": "Enable In-Article Ads for {role}",
+  "@enableInArticleAdsForRoleLabel": {
+    "description": "Label for a checkbox to enable/disable in-article ads for a specific user role.",
+    "placeholders": {
+      "role": {
+        "type": "String",
+        "example": "Guest User"
+      }
+    }
   }
 }