Create a policy, or create it MANAGED from a system scaffold

Account session of a writing workspace member; same-site JSON and an Idempotency-Key are required. With content, the caller authors revision 1 and holds POLICY_OWNER and AUTHOR. With governance MANAGED and no content, the system writes revision 1 as a scaffold with no author, the caller holds POLICY_OWNER and RELEASE_APPROVER (never AUTHOR), the named desk analysts receive their bounded roles, and MANAGED governance takes the scaffold as its baseline, all in one journaled command. Alias kept on the same handler /v1/public/account/workspace/policy-platform.