simplified code across the app and consolidated duplicated helpers

lib/view/pages/talk/details/shared_items_view.dart

@@ -23,19 +23,18 @@ const int _sharedItemsPageSize = 20;
 /// handled separately (split into Bilder/Videos). `location`/`deckcard` are rich
 /// objects without a downloadable file, so they have no place in this view.
 const List<_SharedCategory> _sharedCategories = [
-  _SharedCategory('file', 'Dokumente', _SharedItemsLayout.list),
-  _SharedCategory('voice', 'Sprachnachrichten', _SharedItemsLayout.list),
-  _SharedCategory('audio', 'Audio', _SharedItemsLayout.list),
-  _SharedCategory('recording', 'Aufnahmen', _SharedItemsLayout.list),
-  _SharedCategory('other', 'Sonstiges', _SharedItemsLayout.list),
+  _SharedCategory('file', 'Dokumente'),
+  _SharedCategory('voice', 'Sprachnachrichten'),
+  _SharedCategory('audio', 'Audio'),
+  _SharedCategory('recording', 'Aufnahmen'),
+  _SharedCategory('other', 'Sonstiges'),
 ];
 
 class _SharedCategory {
   final String objectType;
   final String label;
-  final _SharedItemsLayout layout;
 
-  const _SharedCategory(this.objectType, this.label, this.layout);
+  const _SharedCategory(this.objectType, this.label);
 }
 
 bool _isVideoItem(GetChatResponseObject item) {
@@ -203,7 +202,7 @@ class _SharedItemsViewState extends State<SharedItemsView>
         _SharedItemsTab(
           token: widget.room.token,
           objectType: category.objectType,
-          layout: category.layout,
+          layout: _SharedItemsLayout.list,
           emptyLabel: 'Keine Einträge',
           initialPage: _seedFromOverview(raw),
         ),