web: a photo can sit in every landing section at once

The picker was one dropdown, so a photo lived in exactly one place. The three
destinations are now independent checkboxes on the card, and the column holds
the set as a comma list — the landing page draws a photo in every section it
was ticked into, each still picking one of its own at random per visit.

Ticking nothing is what `off` used to be: the row is kept and the landing page
stops drawing it, which is what the old "not on the landing page" option did.

docker/frontend/src/api.ts

@@ -31,10 +31,10 @@ export interface SavedRecipe {
 }
 
 // Where a curated photo may appear on the landing page. `strip` is the
-// community reel; the rest are the three live slots, each of which shows one
-// random photo out of its set per page load. `off` keeps the row but takes it
-// off the landing entirely — the curator's removal.
-export type PhotoSlot = 'strip' | 'tester' | 'creator' | 'qr' | 'off';
+// community reel; the rest are the three live sections, each of which shows one
+// random photo out of its set per page load. A photo may sit in several at
+// once; an empty set is the curator's removal from the landing.
+export type PhotoSlot = 'strip' | 'tester' | 'creator' | 'qr';
 
 // A strip contribution as the public sees it — the API never puts an email on
 // this shape. `tag`/`title`/`meta` are the frame's own labels (the amber
@@ -43,7 +43,7 @@ export type PhotoSlot = 'strip' | 'tester' | 'creator' | 'qr' | 'off';
 export interface Photo {
   id: number;
   createdAt: string;
-  slot: PhotoSlot;
+  slots: PhotoSlot[];
   tag: string | null;
   title: string | null;
   meta: string | null;
@@ -223,8 +223,11 @@ export const api = {
   adminListPhotos: () => call<{ photos: AdminPhoto[] }>('/admin/photos'),
   adminDeletePhoto: (id: number) => call<void>(`/admin/photos/${id}`, { method: 'DELETE' }),
   adminClearPhotos: () => call<{ removed: number }>('/admin/photos', { method: 'DELETE' }),
-  adminSetPhotoSlot: (id: number, slot: PhotoSlot) =>
-    call<{ id: number; slot: PhotoSlot }>(`/admin/photos/${id}`, { method: 'PATCH', body: JSON.stringify({ slot }) }),
+  adminSetPhotoSlots: (id: number, slots: PhotoSlot[]) =>
+    call<{ id: number; slots: PhotoSlot[] }>(`/admin/photos/${id}`, {
+      method: 'PATCH',
+      body: JSON.stringify({ slots }),
+    }),
 
   // Moderation of an account. Both flags are reversible; `adminDeleteUser` is
   // the final act and takes the account's photos and recipes with it.