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>

scripts/migrate-artist-palette.js

@@ -0,0 +1,20 @@
+require('dotenv').config();
+const fs = require('fs');
+const path = require('path');
+const pool = require('../server/db');
+
+async function main() {
+  const sql = fs.readFileSync(path.join(__dirname, '../db/migrate-artist-palette.sql'), 'utf8');
+  await pool.query(sql);
+  const { rows } = await pool.query(`
+    SELECT column_name FROM information_schema.columns
+    WHERE table_name = 'artists' AND column_name = 'palette_metadata'
+  `);
+  console.log(rows.length ? 'artists.palette_metadata ready' : 'migration may have failed');
+  await pool.end();
+}
+
+main().catch((err) => {
+  console.error(err);
+  process.exit(1);
+});