a gallery is a carousel

It always rendered as one — data-carousel, a snap track, two arrows, driven by
carousel.client.js. The entity was the last thing still calling it something
else, and that collided with the site's own Gallery section: two nav rows
reading Gallery and Galleries, meaning a list of objects and a list of
photograph sets.

GalleriesPanel, GalleryPicker and GalleryItems become Carousels*, the endpoint
becomes /fofos-admin/carousels, the block kind becomes carousel and
subject-gallery becomes subject-carousel. The publish allowlist follows the
renamed tables.

What did NOT move: GALLERY_CONFIG at /fofos-admin/gallery, subjects.ts's
base '/gallery', and home_gallery_media. Those are the Gallery section and the
legacy rows, and both are correct.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/thumbnail.ts

@@ -11,7 +11,7 @@ import { getHeaders } from 'hooks/useClient';
  *
  * ── Why this is a module ──
  *
- * It was copied into GalleriesPanel and again into RecordsPanel, and a third copy was about to go into
+ * It was copied into CarouselsPanel and again into RecordsPanel, and a third copy was about to go into
  * MediaField. Three copies of a URL shape is three places to be wrong about the rung when the ladder
  * changes — which it did, four times in a day.
  */