Add PainterPalette integration, canonical DB schema, and influence UI fixes.

Integrate Inputs/PainterPalette.csv for artist metadata and influence links, add db/schema.sql with server/migrate.js, letterbox influence panel thumbnails, and refresh Titian/Pontormo images.

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

Documentation/basics.md

@@ -59,7 +59,11 @@ Gallery/
 │   ├── fetch-missing-images.js
 │   ├── find-duplicate-paintings.js
 │   ├── audit-influence-duplicates.js
+│   ├── painter-palette-lib.js
+│   ├── import-painter-palette.js
 │   └── image-fetcher.js
+├── Inputs/              # External datasets (e.g. PainterPalette.csv)
+├── Output/              # Generated exports (e.g. paintings.csv)
 ├── data/images/         # Local portraits and paintings (+ thumbs/)
 ├── db/                  # SQL schema and migrations (when present)
 ├── deploy/              # Production nginx + systemd examples
@@ -272,7 +276,7 @@ Opened from the 3D hall (artist or movement wing — click a frame) or from infl
 
 | Layer | What you see |
 |-------|----------------|
-| **Detail** | Centre image, *Influenced By* (left) and *Influenced* (right) — painting thumbnails, artist portraits, or movement swatches — position in catalog (e.g. `3 of 12`) |
+| **Detail** | Centre image, *Influenced By* (left) and *Influenced* (right) — painting thumbnails (full work visible, letterboxed), artist portraits, or movement swatches — position in catalog (e.g. `3 of 12`) |
 | **Art history notes** | Numbered markers on the image (when positioned) plus a note list below — short citations from Gombrich, museum catalogs, Wikipedia, etc. (`painting_annotations` table) |
 | **Fullscreen** | Click the centre image; `Escape` or click anywhere to return to detail only |
 
@@ -292,6 +296,7 @@ Opened from the 3D hall (artist or movement wing — click a frame) or from infl
 
 - **Catalog browsing** (‹ › / arrow keys) walks the current artist’s works earliest → latest. It does **not** change the back target: after browsing several works, **Back to Gallery** still returns directly to the hall.
 - **Influence links** push a new detail layer; **Back** from an influenced work returns to the painting you came from (and from there back to the gallery if applicable).
+- Side-panel influence images use **`object-fit: contain`** so tall or wide works are not cropped (dark letterbox background).
 - The 3D hall stays mounted in the background while detail is open so nothing is lost on return.
 
 ### Debug mode (developer)
@@ -307,7 +312,7 @@ When **Debug mode** is enabled from the home header, painting detail and artist
 - **Movement galleries** complement artist halls: full movement corpus in period-themed wings, entered from the flow diagram.
 - **Influence-based hall links** connect artists through documented painting relationships, grouped by movement at the exit.
 - **3D gallery images** use locally cached files only; slow remote fetches would break realtime rendering.
-- **Influence data** is stored in **`painting_influence_sources`** (directed links from paintings to source paintings, artists, or movements), with optional period fields and citation metadata. Legacy `painting_influences` mirrors painting-to-painting edges for scripts only.
+- **Influence data** is stored in **`painting_influence_sources`** (directed links from paintings to source paintings, artists, or movements), with optional period fields and citation metadata. Sources include curated scholarship (`art-influences-data.js`) and **PainterPalette** (`discovered_via = painter-palette`). Legacy `painting_influences` mirrors painting-to-painting edges for scripts only.
 
 ## Developer tools (image audit)