the lead photograph, and names for the subject blocks

`collection-cover` draws the FIRST photograph in the gallery, large, beside the words — the shape the
client's sitemap draws. Not a second way to choose one: a gallery is ordered and reordering it is how
the lead changes, which is the rule everywhere else here.

The five subject blocks are places-only, like the contact form and the partner row. They hold nothing
at all — what they draw is the collection the URL names.

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

web/sections/AddComponentDialog.tsx

@@ -30,6 +30,7 @@ export type ComponentKind =
   | 'contact-form'
   | 'partners'
   | 'collections'
+  | 'collection-cover'
   | 'collection-title'
   | 'collection-description'
   | 'collection-specs'
@@ -42,6 +43,7 @@ export type ComponentKind =
   block: one that is available, adds cleanly, and silently does nothing.
 */
 export const SUBJECT_KINDS: ComponentKind[] = [
+  'collection-cover',
   'collection-title',
   'collection-description',
   'collection-specs',
@@ -96,6 +98,7 @@ export const CHOICES: Choice[] = [
     They hold nothing — not even a reference. The subject is the URL, so one block draws a different
     collection on every request, and that is what lets one arrangement serve all of them.
   */
+  { kind: 'collection-cover', label: 'Its lead photograph', hint: 'The first in its gallery, large', Icon: Image },
   { kind: 'collection-title', label: 'Its name', hint: 'The collection this page is about', Icon: Heading },
   { kind: 'collection-description', label: 'Its description', hint: 'What was written about it', Icon: Type },
   { kind: 'collection-specs', label: 'Its specs', hint: 'Measurement, material, colours, delivery', Icon: Ruler },