Keep pregame lobby chat open for an hour after the game ends

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>

src/Game/Service/GameDashboardService.php

@@ -24,6 +24,7 @@ final class GameDashboardService
 {
     private const READY_TIMEOUT_SECONDS = 60;
     private const LOBBY_MESSAGE_MAX_LENGTH = 500;
+    private const LOBBY_CHAT_GRACE_PERIOD_SECONDS = 3600;
 
     public function __construct(
         private readonly GameRepository $gameRepository,
@@ -302,9 +303,32 @@ final class GameDashboardService
         return $this->lobbyMessageRepository->findForSession($session);
     }
 
+    /**
+     * The lobby chat is open while a session is still gathering players, and stays
+     * open for a grace period after the game ends so players can wrap up the
+     * conversation before it disappears.
+     */
+    public function isLobbyChatOpen(Session $session): bool
+    {
+        if ($session->getStatus() === SessionStatus::CREATED) {
+            return true;
+        }
+
+        if (!in_array($session->getStatus(), [SessionStatus::WON, SessionStatus::LOST], true)) {
+            return false;
+        }
+
+        $finishedAt = $session->getFinishedAt();
+        if ($finishedAt === null) {
+            return false;
+        }
+
+        return (new \DateTime())->getTimestamp() - $finishedAt->getTimestamp() < self::LOBBY_CHAT_GRACE_PERIOD_SECONDS;
+    }
+
     public function postLobbyMessage(Session $session, User $user, string $content): ?LobbyMessage
     {
-        if ($session->getStatus() !== SessionStatus::CREATED) {
+        if (!$this->isLobbyChatOpen($session)) {
             return null;
         }