fix(home): preview 배포 타입 오류 수정

useReducedMotion 반환값이 boolean | null이라서
Vercel 타입 검사에서 useSoftRevealMotion 호출이 실패했어요.

null 병합으로 boolean 타입을 고정해서
preview 빌드가 안정적으로 통과하게 했어요.

Author: dev-wooyeon

src/features/home/ui/sections/HeroSection.tsx

@@ -226,7 +226,7 @@ export default function HeroSection({
   popularPosts,
 }: HeroSectionProps) {
   const [currentPage, setCurrentPage] = useState(1);
-  const prefersReducedMotion = useReducedMotion();
+  const prefersReducedMotion = useReducedMotion() ?? false;
   const articlePanelRef = useRef<HTMLElement>(null);
   const popularPanelRef = useRef<HTMLElement>(null);
   const seriesPanelRef = useRef<HTMLElement>(null);