Identifier of the model producing the current vectors, e.g.
'multilingual-e5-small'. null when no provider is active. Plugins
that cache derived data should key it by modelId.
true when state === 'ready' and at least one note is indexed.
Indexable notes in the vault (excludes trashed, conflict, locked).
Returned by JoplinAi.getIndexStatus. Lets plugins decide whether to use Joplin's native AI or fall back to their own implementation.