Add package 'river' into the RHAI pipeline onboarding collection.

The package builds successfully via the AIPCC self-service pipeline and has a compatible license for redistribution.

Summary

BSD-3-Clause is OSI Approved, FSF Libre, and matches the permissive pattern — this is *Low Risk / Highly Compatible*.

License: BSD-3-Clause
Redistribution Compatible: YES
Reason: BSD-3-Clause is a permissive, OSI-approved, FSF Libre license that allows free redistribution, including building and distributing binary wheels, with only minimal requirements (retain copyright notice and disclaimer).