The pinned Unassigned section folded the queue query's pending state into
isFetching only, which the section never read. On first mount, once GET /board
resolved while the queue was still paging GET /board/search, the pin announced
"No unassigned work orders." instead of a loading state.
Expose the queue query's own isLoading as unassignedLoading, thread it through
the table data hook, and render an aria-busy loading row while it is true so the
loading and empty states are separately observable.
