Speaks the channel.capnp protocol over the per-daemon Unix socket at
~/.consciousness/channels/<top>.sock. Useful for ad-hoc sends from
shell, tests, and out-of-process tools that don't want to embed a
capnp client.
ch send <channel> <message...>
ch recv <channel> [--all-new] [--min-count N]
Co-Authored-By: Proof of Concept <poc@bcachefs.org>
