Close a template's working life

Keeps the row and everything behind it — the dashboard, the canvas, the apply count — and stops the catalog offering it or asking about it. The third state beside draft and live, for the row that had no exit: discard is permanent and takes the template, its preview board and the record that anyone used it — the boards people built from it are their own copies and keep working — so a curated row that will never be fixed and that nobody wants deleted reported the same fault on every audit run forever, and a check that is always red stops being read.

Reversible: unpublish returns a retired row to draft, which is the same door that means “return this row to draft” from live. Refused on a row the catalog does not own, and on one that is already retired.