fix(card-sorting): add border radius to outer card container

Add borderRadius and overflow: 'hidden' to the outer animated.div
container to properly clip the white background at rounded corners.

Previously only the inner div had border radius, causing the white
background to show square corners bleeding through the shadow.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

apps/web/src/arcade-games/card-sorting/components/PlayingPhaseDrag.tsx

@@ -324,6 +324,8 @@ function AnimatedCard({
         touchAction: 'none',
         userSelect: 'none',
         transition: isDragging ? 'none' : 'box-shadow 0.2s ease',
+        borderRadius: '12px',
+        overflow: 'hidden',
       })}
       style={{
         left: springProps.left.to((val) => `${val}px`),
@@ -346,6 +348,8 @@ function AnimatedCard({
           padding: '12px',
           boxSizing: 'border-box',
           overflow: 'hidden',
+          // Clip content to border-box so rounded corners work properly
+          backgroundClip: 'border-box',
         })}
         dangerouslySetInnerHTML={{ __html: card.svgContent }}
       />