feat: enlarge hand card thumbnails to fill zone height

Scale .hand-thumb from 32x45px to 63x84px so cards fill the
hand zone vertically while maintaining MTG card proportions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lan-client/style.css

@@ -855,9 +855,9 @@ input { font-family: inherit; }
 
 /* Hand card thumbnails inside hand zone */
 .hand-thumb {
-  width: 32px;
-  height: 45px;
-  border-radius: 3px;
+  width: 63px;
+  height: calc(var(--card-h) - 4px);
+  border-radius: 4px;
   overflow: hidden;
   flex-shrink: 0;
   cursor: pointer;