Clarify that workplan_id is preferred and workstream_id is a legacy wire-compat alias until legacy-meter retires it.
STATE-WP-0065 renamed progress_event.workstream_id to workplan_id in state-hub; the list endpoint now maps both query params to the model column.
Extract the first reusable slice (models, schemas, routers, MCP, migrations) from state-hub with INTENT/SCOPE, agent instructions, workplan, and aligned inter_hub capability registry index.
