List contacts (cursor-paginated)

curl 'https://api.expiryedge.com/v2/contacts?updated_since=2026-09-01T00%3A00%3A00Z&limit=50' \
  -H "Authorization: Bearer $EXPIRYEDGE_API_KEY"

{
  "data": [
    {
      "id": "c_8Hk2pQ",
      "organization_id": "org_northwind",
      "user_id": "u_71bXq",
      "first_name": "Priya",
      "last_name": "Shah",
      "email": "priya.shah@northwinddental.example",
      "sms_phone": "+15550123456",
      "whatsapp_phone": null,
      "contact_type": "Staff",
      "job_title": "Practice Manager",
      "timezone": "America/New_York",
      "contact_group": "Licensing",
      "is_default": false,
      "email_opt_in": true,
      "sms_opt_in": true,
      "whatsapp_opt_in": false,
      "sendNotifications": true,
      "created_at": "2026-09-27T14:05:00.000Z",
      "updated_at": "2026-09-27T14:05:00.000Z"
    }
  ],
  "next_cursor": "string",
  "has_more": true
}