undelivered rows are always kept regardless of age (still in flight).
sweep runs immediately on serve start then every hour. logs row count
when non-zero. keep_secs is hard-coded for now (30 days); can be
config-driven later if a host wants to retain more / less for audit.
new mcp tool on the manager surface that queues a question on the
dashboard and returns the question id immediately. operator submits an
answer via /answer-question/<id>; the dashboard fires
HelperEvent::OperatorAnswered { id, question, answer } into the manager
inbox so the next turn picks it up.
also: fix async-form button stuck on spinner after successful submit
(refreshState skipped re-rendering, so the button was never re-enabled).