feat(ui): replace close icon with back icon in app bars

- Update leading icon from close (X) to back arrow in AppBar of SavedFiltersPage, SavedHeadlinesPage, and SettingsPage
- Improve user experience by providing a more intuitive navigation indication

Author: fulleni

lib/account/view/saved_filters_page.dart

@@ -27,7 +27,7 @@ class SavedFiltersPage extends StatelessWidget {
     return Scaffold(
       appBar: AppBar(
         leading: IconButton(
-          icon: const Icon(Icons.close),
+          icon: const Icon(Icons.arrow_back),
           onPressed: () {
             context.pop();
           },

lib/account/view/saved_headlines_page.dart

@@ -29,7 +29,7 @@ class SavedHeadlinesPage extends StatelessWidget {
     return Scaffold(
       appBar: AppBar(
         leading: IconButton(
-          icon: const Icon(Icons.close),
+          icon: const Icon(Icons.arrow_back),
           onPressed: () {
             context.pop();
           },

lib/settings/view/settings_page.dart

@@ -25,7 +25,7 @@ class SettingsPage extends StatelessWidget {
     return Scaffold(
       appBar: AppBar(
         leading: IconButton(
-          icon: const Icon(Icons.close),
+          icon: const Icon(Icons.arrow_back),
           onPressed: () {
             context.pop();
           },