Add checkup review flags, duplicate detection, and corrected painting images.

Introduce checkup_checked/checkup_fixed on paintings with Checkup page filters and API. Fixed paintings auto-mark as reviewed. Add find-duplicates tooling and document debug/checkup workflow. Include Botticelli and Michelangelo image fixes from checkup.

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

Documentation/API.md

@@ -204,6 +204,112 @@ Returns the image bytes with `Cache-Control: public, max-age=86400`, or `404` if
 
 ---
 
+## Developer image audit
+
+Routes for the **Checkup** page and **Debug mode** on painting detail. Register `GET /api/paintings/checkup` **before** `GET /api/paintings/:id` so `"checkup"` is not parsed as a painting id.
+
+### `GET /api/paintings/checkup`
+
+Full-catalog audit table for the Checkup UI.
+
+**Response**
+
+```json
+{
+  "paintings": [
+    {
+      "id": 36,
+      "title": "Trinity",
+      "artist_name": "Andrei Rublev",
+      "year": 1411,
+      "gallery_file": "paintings/Andrei_Rublev_Trinity.jpg",
+      "gallery_preview": "paintings/thumbs/Andrei_Rublev_Trinity_thumb.jpg",
+      "detail_file": "paintings/Andrei_Rublev_Trinity.jpg",
+      "detail_preview": "paintings/thumbs/Andrei_Rublev_Trinity_thumb.jpg",
+      "detail_on_demand": false,
+      "gallery_file_exists": true,
+      "detail_file_exists": true,
+      "checked": false,
+      "fixed": false
+    }
+  ],
+  "total": 1201
+}
+```
+
+| Field | Meaning |
+|-------|---------|
+| `checked` | Reviewed in checkup workflow (`checkup_checked`) |
+| `fixed` | Image replaced via Fix (`checkup_fixed`) |
+| `detail_on_demand` | `true` when detail would use `GET /api/paintings/:id/image?size=full` |
+| `gallery_file_exists` / `detail_file_exists` | Disk check under `IMAGE_DIR` |
+
+---
+
+### `PATCH /api/paintings/:id/checkup-flags`
+
+Update review flags. Body: `{ "checked"?: boolean, "fixed"?: boolean }` — at least one field required.
+
+Setting `fixed: true` also sets `checked: true`. While `fixed` is true, the API rejects clearing `checked`.
+
+**Response**
+
+```json
+{ "checked": true, "fixed": false }
+```
+
+---
+
+### `GET /api/paintings/:id/debug-image-search`
+
+Google-family image search for debug / checkup (Custom Search → Google Arts & Culture → scrape → DuckDuckGo). Used by **Search visible** on the Checkup page and the debug panel on painting detail.
+
+**Response**
+
+```json
+{
+  "query": "Andrei Rublev Trinity painting",
+  "imageUrl": "https://…",
+  "source": "google-arts",
+  "pageUrl": "https://…"
+}
+```
+
+---
+
+### `POST /api/paintings/:id/fix-image`
+
+Download a remote URL and replace the painting’s local full image + thumbnail. Sets `checkup_fixed = true` and `checkup_checked = true`.
+
+**Body**
+
+```json
+{ "imageUrl": "https://…" }
+```
+
+**Response**
+
+```json
+{
+  "imagePath": "paintings/Artist_Title.jpg",
+  "thumbnailPath": "paintings/thumbs/Artist_Title_thumb.jpg",
+  "fixed": true,
+  "checked": true
+}
+```
+
+---
+
+### `GET /api/debug/image-proxy`
+
+Proxy a remote image URL for debug preview (avoids hotlink / CORS blocks in the browser).
+
+**Query:** `url` — must be `http://` or `https://`
+
+Returns image bytes with appropriate `Content-Type`.
+
+---
+
 ## Frontend helpers
 
 The React client wraps these endpoints in `client/src/api/client.ts`:
@@ -220,3 +326,8 @@ The React client wraps these endpoints in `client/src/api/client.ts`:
 | `imageUrl(path)` | `/images/<path>` or placeholder |
 | `galleryImageUrl(painting)` | Local thumb/full only (3D) |
 | `paintingImageUrl(painting)` | Local file or on-demand API |
+| `api.getPaintingCheckup()` | `GET /api/paintings/checkup` |
+| `api.updatePaintingCheckupFlags(id, flags)` | `PATCH /api/paintings/:id/checkup-flags` |
+| `api.getPaintingDebugImageSearch(id)` | `GET /api/paintings/:id/debug-image-search` |
+| `api.fixPaintingImage(id, imageUrl)` | `POST /api/paintings/:id/fix-image` |
+| `debugImageProxyUrl(imageUrl)` | `GET /api/debug/image-proxy?url=…` |