fix: replace deprecated Alert `message` prop with `title`

antd v6 deprecated the `message` prop on Alert in favor of `title`.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/components/OfflineBanner/index.tsx

@@ -25,7 +25,7 @@ const OfflineBanner: React.FC = () => {
       type="warning"
       banner
       closable={false}
-      message={getIntl().formatMessage({
+      title={getIntl().formatMessage({
         id: 'app.network.offline',
         defaultMessage:
           'You are currently offline. Some features may be unavailable.',