Fix offline banner: Snapshot's timestamp field is updatedAt

The previous commit referenced a non-existent generatedAt and slipped
past a grep-based gate (grep exit 0 on finding the error). Build gate
checked by exit code from here on.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/app/RootLayout.tsx

@@ -92,11 +92,11 @@ export function LanguageToggle() {
 function OfflineBanner() {
   const { t, kickoffDay, kickoffTime } = useFormat();
   const status = useTournamentStore((s) => s.status);
-  const generatedAt = useTournamentStore((s) => s.snapshot?.generatedAt);
-  if (status !== 'offline' || !generatedAt) return null;
+  const updatedAt = useTournamentStore((s) => s.snapshot?.updatedAt);
+  if (status !== 'offline' || !updatedAt) return null;
   return (
     <div className="border-b border-warning/30 bg-warning/10 px-4 py-1.5 text-center text-xs text-muted" role="status">
-      {fmt(t.common.offlineBanner, { time: `${kickoffDay(generatedAt)} ${kickoffTime(generatedAt)}` })}
+      {fmt(t.common.offlineBanner, { time: `${kickoffDay(updatedAt)} ${kickoffTime(updatedAt)}` })}
     </div>
   );
 }