Get a template (or one frozen version of it)

{id} is a template id (or your own slug) for the current version, or {id}@{version} for one specific version — the same spelling render_template accepts as templateId, so what a job rendered with can always be read back. Built-ins have exactly one version.

An earlier version comes back as a document whose id is {id}@{version}, without slug, description or updatedAt — those belong to the template, not to a version of it.