End a partnership keeping every partner grant as a direct membership (Greentally staff only)

Requires partner.ops (impersonated sessions and API keys are refused); 404 while PARTNERS_ENABLED is off. The link ends (end_reason converted), every partner grant ends with revoked_by converted, the Core grants, account memberships and Clerk memberships stay with the same roles (partnerId is cleared from the membership metadata), and billing returns to the client's own balance at once. 409 GRANTS_NOT_SYNCED while any grant is not in Clerk (pending, failed or revoking); nothing changes. A Clerk failure while clearing partnerId is listed in metadataErrors; calling the route again retries only those clearings (convertedGrants 0, no new audit row). 404 NO_PARTNERSHIP when the client has no active partner and nothing is left to retry.