fix(auth): remove duplicate headings and subtitle on register page

src/components/auth/auth-landing.tsx

@@ -81,7 +81,7 @@ export interface AuthLandingCopy {
 	/** Optional success notice rendered above the form (e.g. "registered"). */
 	notice?: ReactNode;
 	promoTitle: ReactNode;
-	promoSubtitle: ReactNode;
+	promoSubtitle?: ReactNode;
 	usersOnlineLabel: string;
 	whoIsOnlineLabel: string;
 	newestCitizensLabel: string;