Add saved payout destination UX and service contracts (#54)

frontend/app/lib/workspace/copy.dart

@@ -48,6 +48,7 @@ String fundsText(
         _ => l.wFailedOutgoing,
       };
 String walletError(AppLocalizations l, WalletError e) => switch (e) {
+  WalletError.destinationChanged => l.dQuoteChanged,
   WalletError.invalidAmount => l.wInvalidAmount,
   WalletError.insufficientFunds => l.wInsufficient,
   WalletError.limitExceeded => l.wLimitError,