expandReplies method
Expands replies for a comment by fetching them from the server.
Loads all replies for the specified comment and updates the comment's Comment.replies list.
commentId is the ID of the comment to expand replies for.
If the comment is not found, this method does nothing.
Implementation
Future<void> expandReplies(String commentId) async {
final index = _comments.indexWhere((c) => c.id == commentId);
if (index != -1) {
final replies = await controller.getReplies(commentId);
_comments[index] = _comments[index].copyWith(replies: replies);
notifyListeners();
}
}