Get all customers

{
  "customers": [
    {
      "name": "John Doe",
      "external_id": "ext_cust_12345",
      "email": "abc@test.com",
      "billing_entity_code": "acme_inc",
      "address": {
        "line1": "123 Main St",
        "line2": "Apt 4B",
        "city": "New York",
        "state": "NY",
        "postal_code": "10001",
        "country": "US"
      },
      "phone": "+1-234-567-8900",
      "payment_method_token": "pm_visa_4242",
      "payment_method_type": "CARD",
      "taxes": [
        {
          "name": "TVA",
          "rate": "20.00",
          "description": "French standard VAT",
          "code": "standard_vat",
          "id": "1a901a90-1a90-1a90-1a90-1a901a901a90",
          "created_at": "2025-06-01T00:00:00Z"
        }
      ],
      "metadata": [
        {
          "key": "Purchase Order",
          "value": "123456789",
          "display_in_invoice": true
        }
      ]
    }
  ]
}