Get training academy

The Vigilbase Academy enrolments, progress and certificates the Academy synced for a customer (apps/academy/docs/architecture.md section 12.5). The customer is the caller's active organization's; Vigilbase staff pick it with ?customer_id= (the staff customer page) or ?impersonate_customer_id= (View as). Both are ignored for anyone else, as /api/training/me ignores impersonation: they always get their own organization's learning. Staff and the org's owners and admins get every learner with emails; other members only their own enrolments, without emails (lib/academy/learning.ts).