mix bloccs.run path/to/network.bloccs [--message <json>] [--port <name>]Compiles the network, starts the supervisor, and (optionally) feeds a
single JSON message into the named exposed input port (defaults to the
first [expose].in entry, or the first port of the first node).
Without --message, the task starts the tree and runs an IEx-like wait
loop so you can poke at it from outside (use IEx attaches or test scripts).