It is impossible to use message translation in a model callbacks

Code example:

```
User.beforeUpdate = (next) ->
@errors.add 'password', t('passport.failure.invalid_password_format')
next()
```

I get:

```
this.errors.add('password', t('passport.failure.invalid_password_forma
^
ReferenceError: t is not defined
```

Look at the model callback code in jugglingdb, likely in lib/model.js or similar, to see how callbacks are executed and what scope they have. Check if the translation function 't' is available in that scope or needs to be imported. Examine how other parts of the codebase handle translations, possibly in a localization module. The fix involves making the translation function accessible within callback contexts.

Rédigé par le modèle d'indexation à partir du texte de l'issue.