When a coordinator reaches the maximum number of accounts which can be distributed, the partner should automatically be placed on a waitlist. This would probably be a check on the save signal for authorizations. If we save an authorization and now we've got as many auth objects as accounts_available, set to waitlist. This could also help simplify disallowing approvals at the account number limit (T156807) - we only need to check for waitlist status when working with individual applications.

Also, we can't expect coordinators to pay attention to how many authorizations are active, so we should have an automated check each day that will de-waitlist a partner who has less active (expiry date < today) authorizations than accounts available.