- bind $LVMH_HOST_PI_RUNTIME_DIR/spawn-pi -> /root/.pi/spawn-pi (rw) so
container pi's join the host pi's node mesh (spawn_pi/list_pi_nodes/
send_pi_message now reach across the host/container boundary)
- bind host models.json (when present) over the stale image-baked
fallback so newly added catalog models resolve in spawns