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>

client/src/components/PaintingDetail.css

@@ -113,18 +113,26 @@
 }
 
 .influence-image-btn {
-  display: block;
+  display: flex;
+  align-items: center;
+  justify-content: center;
   width: 100%;
-  padding: 0;
+  min-height: 120px;
+  max-height: 220px;
+  padding: 8px;
   border: none;
   background: #2a1f15;
   cursor: pointer;
+  box-sizing: border-box;
 }
 
 .influence-image-btn img {
-  width: 100%;
-  height: 140px;
-  object-fit: cover;
+  width: auto;
+  height: auto;
+  max-width: 100%;
+  max-height: 200px;
+  object-fit: contain;
+  object-position: center;
   display: block;
   transition: opacity 0.2s;
 }
@@ -180,9 +188,9 @@
 }
 
 .influence-card-artist .influence-portrait-btn img {
-  height: 120px;
-  object-fit: cover;
-  object-position: top center;
+  max-height: 160px;
+  object-fit: contain;
+  object-position: center top;
 }
 
 .influence-period {
@@ -290,9 +298,11 @@
 .influence-card img {
   width: 64px;
   height: 64px;
-  object-fit: cover;
+  object-fit: contain;
+  object-position: center;
   border-radius: 4px;
   flex-shrink: 0;
+  background: rgba(0, 0, 0, 0.25);
 }
 
 .influence-info {