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/EditorPanel.tsx

@@ -62,7 +62,7 @@ export const EditorPanel = () => {
       {/*
         Only where there is a page to look at.
 
-        The toggle sets the width the PREVIEW renders at, and Galleries, Media and Administration have
+        The toggle sets the width the PREVIEW renders at, and Carousels, Media and Administration have
         no preview — the control would be three buttons that do nothing visible. Named here rather
         than read from `usePreviewable`, which is a context inside the detail panel and this is its
         sibling.