fix(ui): give the page-header description the full row on a phone

With three or four icon actions beside the title, the description was
left a ~130px column that wrapped five or six times. Below sm it now
spans the row under the title and actions; from sm up the actions span
both rows exactly as before.

A one-word German title wider than the column beside the actions ran
underneath them; the heading hyphenates by the page language and breaks
as a last resort. Notifications, whose two actions are text links,
moves them under the description on a phone (stackActionsOnPhone).

src/app/notifications/page.tsx

@@ -201,6 +201,7 @@ export default function NotificationsPage() {
           title={t("notifications.title")}
           description={t("notifications.subtitle")}
           actions={headerActions}
+          stackActionsOnPhone
         />
         <EmptyState
           className="max-w-2xl"
@@ -227,6 +228,7 @@ export default function NotificationsPage() {
         title={t("notifications.title")}
         description={t("notifications.subtitle")}
         actions={headerActions}
+        stackActionsOnPhone
       />
 
       {/* Desktop: table layout */}