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/DB_structure.md

@@ -98,6 +98,12 @@ Phases within an artist’s career (e.g. “Blue Period”, “Roman Period”).
 | `thumbnail_path` | VARCHAR(500) | Smaller variant for lists / 3D |
 | `wikipedia_title` | VARCHAR(300) | Used by image fetcher |
 | `sort_order` | INTEGER | |
+| `checkup_checked` | BOOLEAN NOT NULL DEFAULT false | Reviewed in image checkup workflow (UI label: **Reviewed**) |
+| `checkup_fixed` | BOOLEAN NOT NULL DEFAULT false | Image corrected via checkup / debug **Fix** |
+
+When `checkup_fixed` is true, `checkup_checked` is set automatically and cannot be cleared until **Fixed** is off.
+
+Applied by `npm run migrate:checkup-flags` (`db/migrate-checkup-flags.sql`).
 
 ### `painting_influences`
 
@@ -150,7 +156,7 @@ Used by painting detail API (`influencedBy`). Painting-type rows also feed `has_
 ## Indexes
 
 - `artists(movement_id)`, `artists(century)`
-- `paintings(artist_id)`, `paintings(period_id)`
+- `paintings(artist_id)`, `paintings(period_id)`, `paintings(checkup_checked)`, `paintings(checkup_fixed)`
 - `art_movements(era_id)`, `art_movements(start_year, end_year)`
 - `painting_influences(painting_id)`, `painting_influences(influenced_by_painting_id)`
 - `painting_influence_sources(painting_id)`, `painting_influence_sources(source_artist_id)`, `painting_influence_sources(source_movement_id)`