fix(account): ensure widget is mounted before navigating

- Add async handling for interstitial ad trigger
- Check if context is still mounted before navigation
- Improve UX by proceeding with navigation only after ad is closed

Author: fulleni

lib/account/view/manage_followed_items/countries/followed_countries_list_page.dart

@@ -96,12 +96,20 @@ class FollowedCountriesListPage extends StatelessWidget {
                     );
                   },
                 ),
-                onTap: () {
-                  context.read<InterstitialAdManager>().onPotentialAdTrigger();
-                  context.pushNamed(
+                onTap: () async {
+                  // Await for the ad to be shown and dismissed.
+                  await context
+                      .read<InterstitialAdManager>()
+                      .onPotentialAdTrigger();
+
+                  // Check if the widget is still in the tree before navigating.
+                  if (!context.mounted) return;
+
+                  // Proceed with navigation after the ad is closed.
+                  await context.pushNamed(
                     Routes.entityDetailsName,
                     pathParameters: {
-                      'type': ContentType.country.name, // 'topic'
+                      'type': ContentType.country.name,
                       'id': country.id,
                     },
                   );