open-legal-products moves Mike's workflow catalog to YAML

The project has updated how it finds the workflow packs used to build its system workflows. The change replaces the older JSON-based signposts with YAML, keeping Mike aligned with the workflow repository's new packaging format.

This is a small but useful piece of maintenance: the workflow build was successfully rebuilt under the new convention, producing all 24 system workflows. For users, the immediate experience should stay familiar. The value is in reducing friction as the workflow library evolves, so new or updated legal workflows can be recognised consistently rather than falling through a mismatch between repositories.