Collabs, as a third configuration of one panel

The same object as a collection and a gallery piece, so it is a config in
subjects.ts and a one-line panel — no new screen.

Two differences, both deliberate. It has no SPECS: a collab is a project rather
than an object, so there is no measurement or raw material and the form is a
name, an address and a description. And its title column is `project_name`,
which is the client's word and stays — the site's API publishes both that and
`title` so this panel reads one field like every other section, and the
translation lives in one router rather than as a branch in every screen.

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

web/sections/CollabsPanel.tsx

@@ -0,0 +1,5 @@
+import { SubjectPanel } from './SubjectPanel';
+import { COLLABS } from './subjects';
+
+/** Collaborations. The panel is shared with Collections and Pieces — see subjects.ts. */
+export const CollabsPanel = () => <SubjectPanel section={COLLABS} />;