curl -X PATCH https://api.vozagent.ai/v1/contacts/c1a2b3c4... \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{
    "company": "Updated Company",
    "notes": "Follow up next week"
  }'

{
  "id": "c1a2b3c4-d5e6-f7a8-b9c0-d1e2f3a4b5c6",
  "first_name": "John",
  "last_name": "Doe",
  "email": "john@example.com",
  "phone_number": "+15551234567",
  "company": "Updated Company",
  "notes": "Follow up next week",
  "updated_at": "2024-01-15T11:00:00Z"
}