QPay / SocialPay нэгтгэх

Gerege Payment API-г ашиглан төлбөр хүлээн авах.

POST api.gerege.mn/payment/v1/qpay
Authorization: Bearer {access_token}
{
  "amount": 50000,
  "description": "Захиалга #123",
  "callback_url": "https://myapp.mn/payment/callback"
}

// Response:
{
  "qr_code": "data:image/png;base64,...",
  "payment_id": "pay_abc123",
  "expires_in": 300
}

POST api.gerege.mn/payment/v1/socialpay
Authorization: Bearer {access_token}
{
  "amount": 25000,
  "description": "Бараа худалдаа",
  "callback_url": "https://myapp.mn/payment/callback"
}

POST api.gerege.mn/payment/v1/ebarimt
Authorization: Bearer {access_token}
{
  "amount": 50000,
  "vat": 5000,
  "items": [{"name": "Бараа", "qty": 1, "price": 50000}]
}

// Response:
{
  "lottery": "abc123",
  "qr_data": "...",
  "bill_id": "..."
}

POST https://myapp.mn/payment/callback
{
  "event": "payment.completed",
  "payment_id": "pay_abc123",
  "amount": 50000,
  "status": "success"
}