Permanently and immediately erase a single template version.

This is permanent: the version row, all its attached files, all version verification records, and any content no longer referenced by any surviving version or skill version are removed from the live system at once. There is no recovery path. Use POST .../archive if you want a reversible alternative for the whole template.

Encrypted backups age out within the platform's standard retention window (up to three months), so the data is not instantly erased from all systems everywhere, but it is no longer accessible through any product surface after this call.

Serving gate: the version must be unpublished first (DELETE .../versions/{version}). A still-published version cannot be permanently deleted because it is currently served to readers. Use DELETE /v1/templates/{template_ref} to remove the entire template at once.

Version numbers remain monotonic with a gap where the erased version was. Surviving versions are not renumbered.

Returns 200 with {template_id, version, deleted: true}.