delete
https://api.qfp.quantnetwork.net/api/tenants//groups/
Soft-deactivates the group; there is no hard delete, so a group a
policy references resolves to a failure rather than to "no approver".
Idempotent. Members can still be removed from a deactivated
group, but nothing else about it can change.
Requires group:manage, and the path tenant must equal the caller's
tenant_id claim.

