Format d'erreur JSON:API

Toutes les erreurs /api/* suivent ce gabarit :

{
  "jsonapi": { "version": "1.1" },
  "errors": [
    {
      "status": "422",
      "title":  "Missing or invalid attribute",
      "detail": "Attribute 'email' is required and must be a non-empty string.",
      "source": { "pointer": "/data/attributes/email" }
    }
  ]
}

En mode debug (APP_DEBUG=true), les 500 exposent un meta.exception/file/line pour faciliter le diagnostic. Désactiver en prod.