fix(flashcards): fix position snap-back by using api.set before decay

Fixed the issue where cards were snapping back to pickup position:
- Use api.set() to immediately snap spring position to dropped location
- Then apply decay animation with momentum from that position
- Removed problematic 'from' property which doesn't work with decay

The bug was that react-spring's 'from' property is ignored when using
decay: true, causing the spring to animate from its current value rather
than the specified position. Using api.set() first ensures the spring
starts from the correct dropped position.

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

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

apps/web/src/components/InteractiveFlashcards.tsx

@@ -200,6 +200,12 @@ function DraggableCard({ card }: DraggableCardProps) {
         currentPositionRef.current.x = currentPositionRef.current.x + mx
         currentPositionRef.current.y = currentPositionRef.current.y + my
 
+        // First, snap the spring to the dropped position immediately
+        api.set({
+          x: currentPositionRef.current.x,
+          y: currentPositionRef.current.y,
+        })
+
         // On release, apply momentum with decay physics
         const throwVelocityX = lastVelocityRef.current.vx * 1000
         const throwVelocityY = lastVelocityRef.current.vy * 1000
@@ -209,14 +215,12 @@ function DraggableCard({ card }: DraggableCardProps) {
 
         api.start({
           x: {
-            from: currentPositionRef.current.x,
             velocity: throwVelocityX,
-            decay: true,
+            config: { decay: true },
           },
           y: {
-            from: currentPositionRef.current.y,
             velocity: throwVelocityY,
-            decay: true,
+            config: { decay: true },
           },
           scale: 1,
           rotation: throwAngle + 90, // Card aligns with throw direction