fix(notifications): keep the history under a key of its own, so an older build never reads its new shape

A build from before the change renders history rows as text; an object there crashed its
Notifications page after a rollback. The old key is read once while the new one does not exist,
and never written.

frontend/src/lib/notifications.ts

@@ -222,7 +222,9 @@ let cachedUnread = 0;
 
 function load(): Notification[] {
   try {
-    const stored = readAccount<unknown>(HISTORY_KEY, []);
+    // The old key only until the new one exists: its rows carry forward, said text as `raw`.
+    const stored =
+      readAccount<unknown>(HISTORY_KEY, null) ?? readAccount<unknown>(LS.legacyNotifHistory, []);
     if (!Array.isArray(stored)) return [];
     // Restored entries are history only. Mark them dismissed so they don't
     // resurrect as active toasts on reload — their auto-dismiss timers aren't