Firmware's Dispatcher::tryParsePacket drops any payload version above 0
at parse, and core's Packet.read_from now enforces the same rule, so a
version-1 routed ACK can never reach the relay; the wire vector
exercising that unreachable input is removed (header regeneration is
still covered by the remaining vectors, including transport-direct).
The advert fixture also OR'd the version-1 bit into its header; it now
builds the version-0 header that PacketBuilder.create_advert emits.