finish the carousel rename in the panels

Two of these were live: PageBuilderPanel still compared kind === 'gallery' in
two places, so a carousel block's editor and its Choose button were both dead
branches. The type checker could not see them — both compare against string.

The rest is copy somebody reads: "Change gallery", "Name a new gallery",
"Reading the gallery", "Add to this gallery", Home's Gallery heading, and the
"Create Gallery" file action, now "Carousel from folder".

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

web/sections/HomePanel.tsx

@@ -10,7 +10,7 @@ import { MediaPicker } from '../MediaPicker';
 import { useAutosave } from '../useAutosave';
 
 /**
- * The Home page: a hero, an intro, and an ordered gallery.
+ * The Home page: a hero, an intro, and an ordered carousel.
  *
  * ── It edits DEVELOPMENT, and that is the whole model ──
  *
@@ -21,18 +21,18 @@ import { useAutosave } from '../useAutosave';
  *
  * ── The server owns the shape, and every write returns it ──
  *
- * `PATCH /home` and every gallery route answer with the WHOLE payload, so this never patches its own
+ * `PATCH /home` and every carousel route answer with the WHOLE payload, so this never patches its own
  * state from what it sent. That matters more than it looks: the server clears the hero crop when the
  * hero changes, and a client that kept its own copy would go on showing a framing the server had
  * already discarded.
  *
  * ── Ordering is a list, not a field ──
  *
- * `PUT /gallery/order` takes every id in the order they should be. So moving one item sends all of
+ * `PUT /carousel/order` takes every id in the order they should be. So moving one item sends all of
  * them, which is what makes it impossible to end up with two things claiming the same position.
  */
 
-type GalleryItem = {
+type CarouselItem = {
   id: number;
   kind: string;
   url: string;
@@ -45,13 +45,13 @@ type GalleryItem = {
 type Home = {
   hero: { url: string | null; crop: string | null; fit: string | null };
   intro_text: string | null;
-  /** The OLD per-page list. Still returned by the API, and only rendered while no gallery is chosen. */
-  gallery: GalleryItem[];
-  /** Which gallery the carousel shows. Null means the old list above still applies. */
+  /** The OLD per-page list. Still returned by the API, and only rendered while no carousel is chosen. */
+  carousel: CarouselItem[];
+  /** Which carousel the carousel shows. Null means the old list above still applies. */
   carousel_id: number | null;
 };
 
-type Gallery = { id: number; name: string; slug: string; items: unknown[] };
+type Carousel = { id: number; name: string; slug: string; items: unknown[] };
 
 export const HomePanel = () => {
   const client = useClient();
@@ -65,7 +65,7 @@ export const HomePanel = () => {
   const [error, setError] = useState<string | null>(null);
   const [saved, flashSaved] = useFlash();
   const [picking, setPicking] = useState(false);
-  const [carousels, setCarousels] = useState<Gallery[]>([]);
+  const [carousels, setCarousels] = useState<Carousel[]>([]);
 
   /** Every write answers with the whole payload, so this is the only place state is set. */
   const apply = useCallback((data: Home) => {
@@ -91,7 +91,7 @@ export const HomePanel = () => {
   // home payload — a copy there would go stale the moment somebody edited one.
   useEffect(() => {
     void clientRef.current
-      .get<{ data: Gallery[] }>('/fofos-admin/carousels')
+      .get<{ data: Carousel[] }>('/fofos-admin/carousels')
       .then((response) => setCarousels(response.data))
       .catch(() => setCarousels([]));
   }, []);
@@ -119,7 +119,7 @@ export const HomePanel = () => {
   /*
     One Save for everything this page holds in a field.
 
-    The gallery choice is NOT part of it: picking a gallery from the list writes immediately, because a
+    The carousel choice is NOT part of it: picking a carousel from the list writes immediately, because a
     <select> that needs a second press to mean anything is a control people believe they have already
     used. The two fields below are typed, and typing is what Save is for.
   */
@@ -211,7 +211,7 @@ export const HomePanel = () => {
       </section>
 
       <section className="flex flex-col gap-3 rounded-lg border border-border p-4">
-        <h3 className="text-sm font-medium">Gallery</h3>
+        <h3 className="text-sm font-medium">Carousel</h3>
 
         {/*
           A picker, not a list.
@@ -233,19 +233,19 @@ export const HomePanel = () => {
           className="w-full rounded-md border border-border bg-background px-3 py-2 text-xs"
         >
           <option value="">None</option>
-          {carousels.map((gallery) => (
-            <option key={gallery.id} value={gallery.id}>
-              {gallery.name} · {gallery.items.length} item{gallery.items.length === 1 ? '' : 's'}
+          {carousels.map((carousel) => (
+            <option key={carousel.id} value={carousel.id}>
+              {carousel.name} · {carousel.items.length} item{carousel.items.length === 1 ? '' : 's'}
             </option>
           ))}
         </select>
 
-        {/* Only while it is true: the old rows are what renders until a gallery is chosen, and saying so
+        {/* Only while it is true: the old rows are what renders until a carousel is chosen, and saying so
             beats a carousel that appears to come from nowhere. */}
-        {home.carousel_id === null && home.gallery.length > 0 && (
+        {home.carousel_id === null && home.carousel.length > 0 && (
           <p className="text-xs text-muted-foreground/70">
-            Showing {home.gallery.length} item{home.gallery.length === 1 ? '' : 's'} from the old
-            per-page list. Choosing a gallery replaces it.
+            Showing {home.carousel.length} item{home.carousel.length === 1 ? '' : 's'} from the old
+            per-page list. Choosing a carousel replaces it.
           </p>
         )}
       </section>