Create Customer

curl --request POST \
  --url https://api.withflex.com/v1/customers \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "customer": {
    "first_name": "John",
    "last_name": "Doe",
    "email": "joh.doe@example.com",
    "phone": "+15555555555",
    "employer": "Flex",
    "shipping": {
      "line1": "<string>",
      "line2": "<string>",
      "city": "<string>",
      "state": "<string>",
      "postal_code": "<string>",
      "country": "<string>"
    },
    "checkout_session_id": "<string>"
  }
}'

{
  "customer": {
    "customer_id": "fcus_01HACM7FZ1084XB1GB6053VM0D",
    "first_name": "John",
    "last_name": "Doe",
    "email": "joh.doe@example.com",
    "phone": "+15555555555",
    "employer": "Flex",
    "shipping": {
      "shipping_address_id": "<string>",
      "line1": "<string>",
      "line2": "<string>",
      "city": "<string>",
      "state": "<string>",
      "postal_code": "<string>",
      "country": "<string>"
    },
    "created_at": "<string>",
    "test_mode": true
  }
}