CHW-4313 ExceptionNotRenewable

only vulnerability-exception policies can be renewed; other policy types have no expiry to extend

Default message: only vulnerability-exception policies can be renewed; other policy types have no expiry to extend
HTTP status: 400 (client)

Problem. /renew was called on a policy that is not a vulnerability-exception allow policy. Cause. Only vulnerability exceptions have an expiry window that renewal extends; other policy types are renewed by editing them. Fix. Use PATCH /api/exceptions for non-vulnerability policies. HTTP 400.