web: show each chat message's seq number right of its date
tsk-0aadqqwe8jvt open
Requested by the maintainer (2026-11-03): in chats (the chat with one's own agent and group chats) every message shows its event seq number to the right of its date/time, e.g. 19:04 · #54306.
Why: agents cite messages by seq ("seq 54246"); humans need to find them in the chat.
- Small, muted, same line as the timestamp; not part of the message text.
- Selectable/copyable as plain number.
- Smoke case for one message showing its seq; e2e/a11y stay green (contrast).
- If the message payload in the chat view lacks the seq, say so on the card before touching the hub.