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/pages/Balance.tsx

@@ -40,7 +40,7 @@ const WalletIcon = ({ className = 'h-8 w-8' }: { className?: string }) => (
 
 export default function Balance() {
   const { t } = useTranslation();
-  const { refreshUser } = useAuthStore();
+  const refreshUser = useAuthStore((state) => state.refreshUser);
   const queryClient = useQueryClient();
   const { formatAmount, currencySymbol } = useCurrency();
   const [searchParams] = useSearchParams();