One descriptor table (activity-kinds.mjs) decides each job kind's pill
verb, toasts, line, tiles, outcomes, openable rows and labels; the
store re-exports it. The scan and image tagging views are unchanged.
A thumbnail job counts Generated, Skipped and Errors, reads
"Generating thumbnails" in the pill and "Thumbnails finished · N
generated · M errors" when it ends.
Any other kind (the health check, a held legacy-page operation) gets
the generic descriptor with no tiles and no Results, instead of the
scan's zero tiles. A running job without a known total shows an
indeterminate progress bar and no percentage, and only a job the
server can cancel shows Cancel.