TET-1667 Conversations page improvements

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch.
_{Learn more about Cursor Agents}

None of this is blocking, but noticed while clicking through the UI:

• it's hard to understand which conversation comes from which agent, hence the filtering is a bit hard to navigate. Should we add the agent name(s) into a column?
• the agent name that is displayed in the drawer, is not filter-able in the new dropdown somehow? example trace - feels quite confusing

Thanks for checking it out! Created an issue for myself, will handle it in the followup.