Changes to Export the items that have one or more failed-ingest images as the standard item xlsx (same columns as M:IO.CommonAPI.Controllers.v1.Catalog.ItemsController.GetItemsExcel(System.Nullable{System.Guid},IO.Catalog.Contracts.DTO.ItemSearchFilter,System.Threading.CancellationToken)), so the user can correct the data offline (e.g. fix dead image URLs) and re-import via the bulk-file endpoint. Scoped like the failed-images grid: honours the same search filter, covers all item types, and is not service-scoped. Serves the file inline for small result sets and queues a background export job for large ones (same gating as M:IO.CommonAPI.Controllers.v1.Catalog.ItemsController.GetItemsExcel(System.Nullable{System.Guid},IO.Catalog.Contracts.DTO.ItemSearchFilter,System.Threading.CancellationToken)). Portal only.