The CLI read the poll cursor from `lastId` while the server sends
`last_id`, so the cursor stayed at 0 and every poll returned the
whole queue at once. It now reads `last_id`.
/names decodes the member objects the server sends and prints each
nick with `@` for an operator or `+` for a voiced member. /list
prints each channel's name and topic, since the server sends no
member count. StateResponse.Channels decodes channel objects.
/topic with no text prints a usage line and sends nothing, because
the HTTP API has no topic query and a TOPIC without text gets 461.
The help says "Set topic".
The client tests serve the bodies the handlers send, so a wrong JSON
tag in types.go fails a test; another test covers the /names prefixes.
Model: opus-5-5
