GetCourse rejects a zero payment («Платеж не может быть нулевым»), so on offers
without «Завершать заказ автоматически» a 0₽ deal stayed «Новый» (no access) while
gc_pay_order / gc_create_order complete:true reported OK: the success regex matched
«Завершен»/«Платеж получен» in the user's feed of OTHER deals on the same card.

- payDeal: amount 0 → complete via status `payed` («Завершен»); amount > 0 →
  received payment as before. Success is read from the deal's own «Статус:» field
  after a reload; GetCourse form errors are surfaced in the FAIL message.
- setOrderStatus: add `payed` to gc_set_order_status; ok only when the reloaded
  card shows the requested status (was always ok:true).
- Docs: the status dropdown DOES have «Завершен» — drop the "no «Оплачен», only
  payment" claim.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>