feat(localization): add generic search hint text and update headlines search

- Add generic search hint text for localization in app_ar.arb and app_en.arb
- Update headlines search page to use localized search hint text
- Remove TODO comment regarding search hint text localization

Author: fulleni

lib/headlines-search/view/headlines_search_page.dart

@@ -187,8 +187,7 @@ class _HeadlinesSearchViewState extends State<_HeadlinesSearchView> {
                 controller: _textController,
                 style: appBarTheme.titleTextStyle ?? textTheme.titleMedium,
                 decoration: InputDecoration(
-                  // TODO(fulleni): Create a similar localization extension for hint text.
-                  hintText: 'Search...',
+                  hintText: l10n.searchHintTextGeneric,
                   hintStyle: textTheme.bodyMedium?.copyWith(
                     color:
                         (appBarTheme.titleTextStyle?.color ??

lib/l10n/app_localizations.dart

@@ -998,6 +998,12 @@ abstract class AppLocalizations {
   /// **'e.g., AI advancements, Mars rover...'**
   String get searchHintTextHeadline;
 
+  /// Generic hint text for search input fields
+  ///
+  /// In en, this message translates to:
+  /// **'Search...'**
+  String get searchHintTextGeneric;
+
   /// Hint text for searching categories
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_ar.dart

@@ -487,6 +487,9 @@ class AppLocalizationsAr extends AppLocalizations {
   String get searchHintTextHeadline =>
       'مثال: تطورات الذكاء الاصطناعي, مركبة المريخ...';
 
+  @override
+  String get searchHintTextGeneric => 'بحث...';
+
   @override
   String get searchHintTextCategory => 'مثال: تكنولوجيا, رياضة, مالية...';
 

lib/l10n/app_localizations_en.dart

@@ -488,6 +488,9 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get searchHintTextHeadline => 'e.g., AI advancements, Mars rover...';
 
+  @override
+  String get searchHintTextGeneric => 'Search...';
+
   @override
   String get searchHintTextCategory => 'e.g., Technology, Sports, Finance...';
 

lib/l10n/arb/app_ar.arb

@@ -618,6 +618,10 @@
     "@searchHintTextHeadline": {
         "description": "Hint text for searching headlines"
     },
+    "searchHintTextGeneric": "بحث...",
+    "@searchHintTextGeneric": {
+        "description": "Generic hint text for search input fields"
+    },
     "searchHintTextCategory": "مثال: تكنولوجيا, رياضة, مالية...",
     "@searchHintTextCategory": {
         "description": "Hint text for searching categories"

lib/l10n/arb/app_en.arb

@@ -619,6 +619,10 @@
     "@searchHintTextHeadline": {
         "description": "Hint text for searching headlines"
     },
+    "searchHintTextGeneric": "Search...",
+    "@searchHintTextGeneric": {
+        "description": "Generic hint text for search input fields"
+    },
     "searchHintTextCategory": "e.g., Technology, Sports, Finance...",
     "@searchHintTextCategory": {
         "description": "Hint text for searching categories"