perf: add Zustand selectors to prevent cascading re-renders

Replace all bare useAuthStore(), useBlockingStore(), and
useSuccessNotification() calls with individual field selectors.
This prevents components from re-rendering when unrelated store
fields change.

- 21 useAuthStore usages across 20 files: individual selectors
  for 1-2 fields, useShallow for 3+ fields
- 5 useBlockingStore usages: individual selectors
- 2 useSuccessNotification usages: individual selectors

src/components/TicketNotificationBell.tsx

@@ -33,7 +33,7 @@ export default function TicketNotificationBell({ isAdmin = false }: TicketNotifi
   const { t } = useTranslation();
   const navigate = useNavigate();
   const queryClient = useQueryClient();
-  const { isAuthenticated } = useAuthStore();
+  const isAuthenticated = useAuthStore((state) => state.isAuthenticated);
   const { showToast } = useToast();
   const [isOpen, setIsOpen] = useState(false);
   const dropdownRef = useRef<HTMLDivElement>(null);