Is there a way to resume a thread? On page navigation or refresh it always starts with a new one and the user has to load the last one via history. /v1/chatkit/threads?user=user_xxx only provides created_at but I need a time stamp for the last used thread. My workaround is to get all thread ids per user, loop through them with /v1/chatkit/threads/cthr_xxx/items and look for the most recent item, which results in multiple API calls 