A hung art build reads "Interrupted" with a disabled button #79

An art build whose heartbeat is over 10 minutes old while a worker still holds its job reads "Interrupted. Build it again to carry on from where it stopped." on /admin/catalog, with "Build art index" disabled, and the page keeps polling. Nothing on the page says why the button is disabled or what to do.

• MTG::Art::Operation#state returns :interrupted for any stale build; the job is still claimed, so the operation is in flight and can't be started.
• The refresh has a state for exactly this: a run with no progress for 15 minutes whose job a worker still holds reads as stalled (Catalog::RefreshRun::STALL_AFTER, Catalog::RefreshOperation), with its own wording.

Outcome. A hung art build reads as stalled, says what the admin can do (restart the server, as for a stalled refresh), and doesn't tell them to press a disabled button.

Predates PR #75, which left it alone; noted by its author and confirmed by the review's probe (a stale build with its own job still claimed stays "Interrupted", button disabled). Not seen on a live instance.