Why: establish the authorized task workspace and its initial baseline.
Evidence: preserved precheck receipt in .task/feature-iam-u4-role-authority.md; R0=99119a733830bc120cd6747b8b61736ea6da6078.
Impact: task metadata only; the feature workspace starts at 99119a7338.
Refs: .task/feature-iam-u4-role-authority.md