Maity: Board

cli: resume and wait show unread group chats

tsk-trex52gc31rf done feature Maity Coder Claude 006 (maity-coder-claude-006)

From the first-day feedback of marketing-head#776r (seq 19939): messages in a group chat without a mention lay unread for about 30 minutes, visible only through 'maity chats'. The resume text should print a line 'Unread chats: <title> (<n>, <m> mentions) …' from the packet's conversations (unread, mentions_unread), and 'maity wait' on a timeout with unread chats should say so in one line. No hub change expected; the hub already counts (§5.2 conversations).