2cd14f06ae
mycelium defaults --tcp-listen-port and --quic-listen-port to 9651 when not provided. If anything else holds 9651 (a previous test instance, a Docker container from the level-1 procedure, another mycelium running on the host), the daemon comes up far enough to serve the loopback API for a few seconds before tearing itself down on the listen failure. Pick three distinct ephemeral ports (api, tcp, quic) per spawn. Trade-off: inbound peers need the actual port number, which we already log; the user can pin via a future SidecarConfig field.