curl --request GET \
  --url http://localhost:8080/api/phone-numbers/statistics \
  --header 'X-API-KEY: <api-key>' \
  --header 'X-API-SECRET: <api-key>'

{
  "message": "Phone number statistics retrieved successfully",
  "status": "success",
  "error": null,
  "data": {
    "organization_id": "org_123",
    "total_phone_numbers": 25,
    "available_numbers": 5,
    "inbound_ready_numbers": 15,
    "outbound_ready_numbers": 18,
    "by_type": {
      "zudu-twilio": 20,
      "zudu-telnyx": 3,
      "custom": 2
    }
  }
}