fix: right-click no longer triggers detail window

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/dashboard/TaskCard.tsx

@@ -67,10 +67,12 @@ export function SortableTaskCard({ task, sectionOptions, onSelect }: { task: Tas
   const pointerStart = useRef<{ x: number; y: number } | null>(null);
 
   const handlePointerDown = (e: React.PointerEvent) => {
+    if (e.button !== 0) return; // 좌클릭만
     pointerStart.current = { x: e.clientX, y: e.clientY };
   };
 
   const handlePointerUp = (e: React.PointerEvent) => {
+    if (e.button !== 0) return; // 좌클릭만
     if (!pointerStart.current || isDragging) return;
     const dx = e.clientX - pointerStart.current.x;
     const dy = e.clientY - pointerStart.current.y;