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.