TCP transport
Adds the raw Arrow-IPC TCP transport from vgi-rpc 0.21.0:
- Worker
--tcp [HOST:]PORTserving (emits theTCP:<host>:<port>discovery line; idle-timeout self-shutdown). - Client
transport="tcp"+Client.from_tcp(host, port); catalog calls routed over TCP too.
Raw TCP framing carries no auth/encryption — loopback/trusted networks only; HTTP remains the transport for untrusted networks.