Add A Simple Button menu to the Bitverse Screen if ascii art is disabled

this fixed the issue that was noticed that the current ascii art page is
not possible to navigate with a screen reader

src/BitNode/ui/PortalModal.tsx

@@ -43,6 +43,8 @@ export function PortalModal(props: IProps): React.ReactElement {
       <br />
       <br />
       <Button
+        aria-label={`enter-bitnode-${bitNode.number.toString()}`}
+        autoFocus={true}
         onClick={() => {
           props.enter(router, props.flume, props.destroyedBitNode, props.n);
           props.onClose();