fix(headline-details): add spacing when no similar headlines

- Add SliverToBoxAdapter with SizedBox height of AppSpacing.lg when no similar headlines

Author: fulleni

lib/headline-details/view/headline_details_page.dart

@@ -402,6 +402,10 @@ class _HeadlineDetailsPageState extends State<HeadlineDetailsPage> {
           ),
         ),
       );
+    } else {
+      slivers.add(
+        const SliverToBoxAdapter(child: SizedBox(height: AppSpacing.lg)),
+      );
     }
 
     slivers.addAll([
@@ -466,6 +470,10 @@ class _HeadlineDetailsPageState extends State<HeadlineDetailsPage> {
           ),
         ),
       );
+    } else {
+      slivers.add(
+        const SliverToBoxAdapter(child: SizedBox(height: AppSpacing.lg)),
+      );
     }
 
     Future<void> onSimilarHeadlineTap(Headline similarHeadline) async {