fix build issue

src/components/sections/WingsWhyGrid.tsx

@@ -472,6 +472,7 @@ export default function WingsWhyGrid() {
         },
       });
       playedTimeline = tl;
+      st = tl.scrollTrigger ?? null;
 
       // The energy pulse's own journey — calm and deliberate, ~4.8-5.5s so
       // it glides rather than rushes from the first card to the last.