The chat used to disappear the moment a session left CREATED status.
Sessions now record a finishedAt timestamp when they're won or lost,
and the lobby (with chat) stays reachable via /game/{session} for an
hour afterward instead of immediately redirecting to the win/lose
feedback page. The lobby template shows a distinct "game finished"
header with a link to that feedback page during this window.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
