feat(l10n): add translation for source list filter by headquarters page title

- Add Arabic and English translations for the new page title "Headquarters location"
- Include descriptions for the new translations in both app_ar.arb and app_en.arb files

Author: fulleni

lib/l10n/app_localizations.dart

@@ -1922,6 +1922,12 @@ abstract class AppLocalizations {
   /// **'Filter source list'**
   String get sourceListFilterPageFilterButtonTooltip;
 
+  /// Title for the page where users filter sources by headquarters country.
+  ///
+  /// In en, this message translates to:
+  /// **'Headquarters location'**
+  String get sourceListFilterByHeadquartersPageTitle;
+
   /// The title for the list tile on the account page that navigates to the saved filters management page.
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_ar.dart

@@ -1009,6 +1009,9 @@ class AppLocalizationsAr extends AppLocalizations {
   @override
   String get sourceListFilterPageFilterButtonTooltip => 'تصفية قائمة المصادر';
 
+  @override
+  String get sourceListFilterByHeadquartersPageTitle => 'مكان المقر';
+
   @override
   String get accountSavedFiltersTile => 'الفلاتر المحفوظة';
 

lib/l10n/app_localizations_en.dart

@@ -1010,6 +1010,9 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get sourceListFilterPageFilterButtonTooltip => 'Filter source list';
 
+  @override
+  String get sourceListFilterByHeadquartersPageTitle => 'Headquarters location';
+
   @override
   String get accountSavedFiltersTile => 'Saved Filters';
 

lib/l10n/arb/app_ar.arb

@@ -1426,6 +1426,10 @@
     "@failedToLoadMoreSources": {
         "description": "رسالة خطأ عند فشل تحميل المزيد من المصادر في صفحة التفاصيل"
     },
+    "sourceListFilterByHeadquartersPageTitle": "مكان المقر",
+    "@sourceListFilterByHeadquartersPageTitle": {
+        "description": "عنوان الصفحة التي يقوم فيها المستخدمون بتصفية المصادر حسب بلد المقر."
+    },
     "sourceTypeNewsAgency": "وكالة أنباء",
     "@sourceTypeNewsAgency": {
         "description": "نوع المصدر لوكالة أنباء"

lib/l10n/arb/app_en.arb

@@ -1322,6 +1322,10 @@
     "@sourceListFilterPageFilterButtonTooltip": {
         "description": "Tooltip for the button that opens the source list filter page."
     },
+    "sourceListFilterByHeadquartersPageTitle": "Headquarters location",
+    "@sourceListFilterByHeadquartersPageTitle": {
+        "description": "Title for the page where users filter sources by headquarters country."
+    },
     "accountSavedFiltersTile": "Saved Filters",
     "@accountSavedFiltersTile": {
         "description": "The title for the list tile on the account page that navigates to the saved filters management page."