curl --request GET \
  --url 'https://backend.testeswaffle.org/newsletters/subscriber/usuario@exemplo.com' \
  --header 'Authorization: Bearer seu-token-jwt'

{
  "success": true,
  "data": {
    "subscriber": {
      "id": "sub_123456789",
      "email": "usuario@exemplo.com",
      "name": "João Silva",
      "created_at": "2023-06-15T10:30:00Z",
      "status": "active",
      "beehiiv_id": "bhv_987654321"
    },
    "subscriptions": [
      {
        "newsletter_id": "thenews",
        "newsletter_name": "the news",
        "subscribed_at": "2023-06-15T10:30:00Z",
        "status": "active",
        "source": "referral"
      },
      {
        "newsletter_id": "thebizness",
        "newsletter_name": "the bizness",
        "subscribed_at": "2023-08-20T14:15:00Z",
        "status": "active",
        "source": "organic"
      }
    ],
    "metrics": {
      "total_opens": 145,
      "total_clicks": 32,
      "average_open_rate": 72.5,
      "last_engagement": "2024-01-14T08:45:00Z"
    },
    "referrals": {
      "referred_by": "amigo@exemplo.com",
      "total_referrals": 8,
      "successful_referrals": 5
    }
  }
}