(remote-node addr fn) runs a node on a federation peer. Transport is the fed-sx
boundary, mocked by a peer registry (flow-peer-register!); raises
flow-remote-unreachable / flow-remote-no-fn. Composes with sequence/suspend/retry.
Also fixes conformance.sh to load remote.sx before api.sx.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>