fix(TreeCanvas): remove unused variable updatedTree

Author: CC11001100

src/components/TreeCanvas.tsx

@@ -105,7 +105,7 @@ const TreeCanvas: React.FC<TreeCanvasProps> = ({
     const currentStep = steps[currentStepIndex];
     if (!currentStep || !currentStep.nodeId) return;
 
-    const updatedTree = applyStepToTree(tree.clone(), currentStep);
+    applyStepToTree(tree.clone(), currentStep);
     updatePositions();
 
   }, [currentStepIndex, steps]);