Obtener Etapa

curl -X GET "https://api.whaapy.com/funnel/v1/stages/550e8400-e29b-41d4-a716-446655440000" \
  -H "Authorization: Bearer wha_TU_API_KEY"

{
  "stage": {
    "id": "550e8400-e29b-41d4-a716-446655440000",
    "name": "Qualified",
    "position": 1,
    "color": "#10b981",
    "contact_count": 45,
    "created_at": "2026-01-01T00:00:00Z",
    "updated_at": "2026-01-28T10:00:00Z"
  }
}

{
  "error": "validation_error",
  "message": "ID de etapa inválido"
}

{
  "error": "not_found",
  "message": "Etapa no encontrada"
}