feat(chat): recover a note the agent finished without reading

The pull channel is cooperative — "never read" is an ordinary outcome — but an
unread note used to disappear the moment the turn ended (`showList` required
`isPrompting`), and the next turn then cleared it backend-side. The user's text
went with it, unannounced.

The list now outlives its turn while any note is still pending: it says the
agent finished before reading them, and each row offers "send as message"
(through the existing `onResendAsPrompt` queue hand-off, which auto-flushes
against a connected session) or a dismiss. Delivered rows retire with the turn
they steered.

Retired ids are tombstoned so a re-hydrate cannot bring a row back; the
tombstones clear with the notes on the next turn.

The three strings this needs already ship in all ten locales — they are the
ones the deleted live-feedback bar left behind.