List the member emails an alert can notify.

Returns [{ "email": … }] for your organization — active members only, alphabetised. Gated on alerts:read OR alerts:write rather than users:read, so whoever views or edits alerts can fill in the recipient picker without being able to read user records; only emails come back, never the permissions and ids /users returns. Alert channels can also be pointed at external addresses that are not members — this is the convenience list, not the set of addresses you are allowed to use.