fix(shared): update entity details page arguments in headline tile

- Replace 'entity' parameter with 'entityId' in EntityDetailsPageArguments
- This change affects both topicDetails and sourceDetails routes
- Ensures that only the necessary ID is passed instead of the full object

Author: fulleni

lib/shared/widgets/feed_core/headline_tile_text_only.dart

@@ -151,7 +151,7 @@ class _HeadlineMetadataRow extends StatelessWidget {
               context.push(
                 Routes.topicDetails,
                 extra: EntityDetailsPageArguments(
-                  entity: headline.topic,
+                  entityId: headline.topic.id,
                   contentType: ContentType.topic,
                 ),
               );
@@ -175,7 +175,7 @@ class _HeadlineMetadataRow extends StatelessWidget {
               context.push(
                 Routes.sourceDetails,
                 extra: EntityDetailsPageArguments(
-                  entity: headline.source,
+                  entityId: headline.source.id,
                   contentType: ContentType.source,
                 ),
               );