When a fact expression refers back to an object that was already introduced (the non-first mention), CaseTalk currently uses the substitution reference name when one is given, or falls back to the plain object type name.

With the new article property of object types (ticket 0005664), re-verbalizations can produce more natural references automatically:

1. If a substitution reference name is given, use it (as today - the explicit override).
2. Otherwise, if the object type has an article, refer back with article + name (e.g. "de Klant", "het Vliegtuig").
3. Otherwise keep the current behavior.

The first mention (introduction) of an object stays unchanged.

Because this changes how every expression is rendered (diagrams, expression viewers, reports), the behavior should be controlled by a project option, default off, so existing models keep their current verbalization until explicitly enabled.

This also gives the RegelSpraak/GegevensSpraak export (ticket 0005663) correct Dutch subject references (universeel onderwerp "een X" vs onderwerpverwijzing "de/het X") without extra work.