curl --request POST \
  --url https://{notifuseDomain}/api/contacts.upsert \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "workspace_id": "ws_1234567890",
  "contact": {
    "email": "user@example.com",
    "external_id": "user_12345",
    "timezone": "America/New_York",
    "language": "en-US",
    "first_name": "John",
    "last_name": "Doe",
    "phone": "+15551234567",
    "address_line_1": "123 Main St",
    "address_line_2": "Apt 4B",
    "country": "US",
    "postcode": "10001",
    "state": "NY",
    "job_title": "Software Engineer",
    "lifetime_value": 1250.5,
    "orders_count": 5,
    "last_order_at": "2023-05-15T14:30:00Z",
    "custom_string_1": "Premium tier",
    "custom_string_2": "<string>",
    "custom_string_3": "<string>",
    "custom_string_4": "<string>",
    "custom_string_5": "<string>",
    "custom_number_1": 42,
    "custom_number_2": 123,
    "custom_number_3": 123,
    "custom_number_4": 123,
    "custom_number_5": 123,
    "custom_datetime_1": "2023-06-01T09:00:00Z",
    "custom_datetime_2": "2023-11-07T05:31:56Z",
    "custom_datetime_3": "2023-11-07T05:31:56Z",
    "custom_datetime_4": "2023-11-07T05:31:56Z",
    "custom_datetime_5": "2023-11-07T05:31:56Z",
    "custom_json_1": {
      "preferences": {
        "theme": "dark",
        "notifications": true
      }
    },
    "custom_json_2": {},
    "custom_json_3": {},
    "custom_json_4": {},
    "custom_json_5": {},
    "created_at": "2023-01-15T10:30:00Z",
    "updated_at": "2023-04-22T15:45:00Z"
  }
}'