Add IPv6 link-local address to net_init and info response, use WaitGroup.Go

firmware/firmware.cpp

@@ -51,6 +51,7 @@ int main() {
                 std::copy(uid.id, uid.id + 8, resp.board_id.begin());
                 auto ninfo = w6300::get_net_info();
                 resp.mac = ninfo.mac;
+                resp.link_local = ninfo.lla;
                 usb.send(encode_response(msg->message_id, resp));
                 break;
             }