- migration 202610280004: image_file_no, kind, published_at and parent_refs
on the slot table; the image, News, IndexNow and HTML sitemap settings
- the rebuild stores each page's featured and body images (absolute on the
site, deduplicated, at most 1000) and numbers the rows with images into
sitemap-images-<n>.xml with the per-type files' stable rules
- the index lists the image files while images_enabled is on; the files
route serves them with image:image and image:loc only
