Models blocked by admin policy get their own reason when dropped from the model list

When Claude Code leaves a model out of its model list, it records a reason for dropping it. Models that an organisation's managed policy denies now get the reason "managed_denied". A managed policy is a set of rules an administrator sets for everyone in the organisation. Before this change, those models were recorded under the same reason as models removed by an allowlist, which is a list of models that are allowed. Models dropped because the account is not entitled to them are still recorded as "entitlement_denied", as before.