demo local code

[bennn]

The IRC choreography paper talks about interoperability with local code. Sec 3 & Fig 3 talk about general Java code. Sec 5.1 uses a Java ByteChannel as a concrete example:
https://programming-journal.org/2024/8/8/

Chorex should be able to do this!

Make a demo that imports code from another library / module and uses it to implement part of a choreography (e.g. Alice uses a standard helper function to make a sandwich request.)