Topic feed improvements: pagination, new categories, simplified layout

- Topic feed uses useInfiniteQuery for pagination (cursor-based)
- Curated topics render single feed instead of Top/Latest tabs
- Legacy search-based topics retain tabbed layout
- New categories: entertainment, culture, music, community
- Sidebar trending limit increased to 7
- Topic header title length increased to 30 chars

Author: rudyfraser

src/screens/Search/modules/ExploreTrendingTopics.tsx

@@ -221,6 +221,14 @@ function useCategoryDisplayName(
       return _(msg`Video Games`)
     case 'pop-culture':
       return _(msg`Entertainment`)
+    case 'entertainment':
+      return _(msg`Entertainment`)
+    case 'culture':
+      return _(msg`Culture`)
+    case 'music':
+      return _(msg`Music`)
+    case 'community':
+      return _(msg`Community`)
     case 'news':
       return _(msg`News`)
     case 'other':