Expose the reliable-channel layer through the v0.1.3 FFI:
- channel_create / channel_send / channel_close call the
ReliableChannelManager api (createReliableChannel / send / closeChannel),
marshalling channel id + base64 payload + ephemeral by hand
- channel message received / sent / errored are surfaced by listening to the
channel-layer broker events in start_node and forwarding them through
callEventCallback (received payload base64-encoded), dropped in stop_node
Stays on nim-ffi v0.1.3 (no typed/CBOR rewrite).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>