Update reaction strip to show only top 3 reactions with full functionality

- Add logic to sort reactions by count and take top 3
- Maintain full ReactionStrip functionality (toggle, add, tooltips)
- Only limit display to top 3 most popular reactions
- Keep all reaction state management and API calls
- Preserve visual design and interactions
- Add button still available for adding new reactions

sojorn_app/lib/widgets/post/post_actions.dart

@@ -203,12 +203,19 @@ class _PostActionsState extends ConsumerState<PostActions> {
   Widget build(BuildContext context) {
     final allowChain = widget.post.allowChain && widget.post.visibility != 'private' && widget.onChain != null;
 
+    // Get top 3 reactions by count
+    final sortedReactions = _reactionCounts.entries.toList()
+      ..sort((a, b) => b.value.compareTo(a.value));
+    final topReactions = Map.fromEntries(
+      sortedReactions.take(3)
+    );
+
     return Column(
       crossAxisAlignment: CrossAxisAlignment.start,
       children: [
-        // Reactions section - full width
+        // Reactions section - full width, but only top 3
         ReactionStrip(
-          reactions: _reactionCounts,
+          reactions: topReactions,
           myReactions: _myReactions,
           reactionUsers: {},
           onToggle: (emoji) => _toggleReaction(emoji),