Add public curator notes and U-shaped hall wall hang.

Paintings get editable curator notes with brass plates in the 3D hall, and visit order now uses the far/end wall between left and right.

Co-authored-by: Cursor <cursoragent@cursor.com>

Documentation/API.md

@@ -73,6 +73,7 @@ These return **`401`** with `{ "error": "Curator login required" }` without a va
 | `GET /api/artists/:id/debug-portrait-search` (+ `/more`) | — |
 | `GET /api/debug/image-proxy` | — |
 | `PATCH /api/paintings/:id/checkup-flags` | `painting.checkup_flags` |
+| `PATCH /api/paintings/:id/curator-notes` | `painting.update_curator_notes` |
 | `PATCH /api/artists/:id/checkup-flags` | `artist.checkup_flags` |
 | `POST /api/paintings/:id/fix-image` | `painting.fix_image` |
 | `POST /api/paintings/:id/clear-image` | `painting.clear_image` |
@@ -593,6 +594,7 @@ Painting detail with influence graph neighbours.
     "thumbnail_cache_key": 1739123456790,
     "checkup_checked": false,
     "checkup_fixed": false,
+    "curator_notes": "",
     "has_influence_links": true
   },
   "influencedBy": [
@@ -698,6 +700,22 @@ Full-catalog audit table for the Checkup UI.
 
 ---
 
+### `PATCH /api/paintings/:id/curator-notes`
+
+Update public curator notes for a painting.
+
+**Body**
+
+```json
+{ "curatorNotes": "Optional editorial text…" }
+```
+
+`curatorNotes` must be a string (trim applied; empty string clears the notes).
+
+**Response:** `{ "curatorNotes": "…" }`
+
+**Audit:** `painting.update_curator_notes`
+
 ### `PATCH /api/paintings/:id/checkup-flags`
 
 Update review flags. Body: `{ "checked"?: boolean, "fixed"?: boolean }` — at least one field required.
@@ -877,6 +895,7 @@ The React client wraps these endpoints in `client/src/api/client.ts`. All reques
 | `validateDebugUploadFile(file)` | Client-side size/type check before base64 upload |
 | `api.getPaintingCheckup()` | `GET /api/paintings/checkup` |
 | `api.updatePaintingCheckupFlags(id, flags)` | `PATCH /api/paintings/:id/checkup-flags` |
+| `api.updatePaintingCuratorNotes(id, curatorNotes)` | `PATCH /api/paintings/:id/curator-notes` |
 | `api.getPaintingDebugImageSearch(id)` | `GET /api/paintings/:id/debug-image-search` |
 | `api.getPaintingDebugImageSearchMore(id, limit?)` | `GET /api/paintings/:id/debug-image-search/more` |
 | `api.fixPaintingImage(id, imageUrl, context?)` | `POST /api/paintings/:id/fix-image` |