Wownero: route MoneroAccountListViewModel.selected to wownero API

The .selected computed getter always called monero!.getCurrentAccount(_wallet),
which does an internal 'wallet as MoneroWallet' cast and threw
'WowneroWallet is not a subtype of MoneroWallet' whenever the dashboard
CardsView Observer rebuilt for a Wownero wallet. The .accounts getter
above already dispatched correctly by wallet.type; .selected didn't.

Now matches the same monero/wownero dispatch pattern.

lib/view_model/monero_account_list/monero_account_list_view_model.dart

@@ -58,7 +58,9 @@ abstract class MoneroAccountListViewModelBase with Store {
 
   @computed
   AccountListItem get selected {
-    final currentId = monero!.getCurrentAccount(_wallet).id;
+    final currentId = _wallet.type == WalletType.wownero
+        ? wownero!.getCurrentAccount(_wallet).id
+        : monero!.getCurrentAccount(_wallet).id;
     return accounts.firstWhere((item) => item.id == currentId);
   }