WebSocket event handlers for comment:created and activity:created
appended new entries to the end of the timeline array without sorting.
When events arrived out of order (e.g. agent replying rapidly), comments
displayed out of chronological order.
Sort the timeline by created_at after each append to maintain correct
chronological ordering.
Closes#1032
commentToTimelineEntry() was dropping the attachments field, and
comment-card never rendered entry.attachments. Attachments uploaded
through the CLI (not embedded in markdown) were invisible in the UI.
- Add attachments to commentToTimelineEntry() conversion
- Add AttachmentList component that renders standalone attachments
(skipping those already referenced in the markdown content)
- Render AttachmentList in both CommentRow and CommentCard