Create an invoice

curl -X POST "https://api.live.paisr.tech/v2/invoices" \
  -H "Authorization: Bearer <access_token>" \
  -H "User-Agent: MyApp/1.0" \
  -H "Content-Type: application/json" \
  -d '{
  "customer": "john@example.com",
  "summary": "Invoice for services rendered",
  "currency": "SRD",
  "due": "In 3 days",
  "line_items": [
    {
      "description": "string",
      "quantity": 1,
      "unit_price": 0
    }
  ]
}'

{
  "success": true,
  "data": {
    "id": "inv_123456",
    "status": "unpaid",
    "session": {
      "url": "https://checkout.paisr.tech/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9",
      "expires_at": "2024-01-15T10:30:00Z"
    }
  }
}