feat: react-swipeable 설치 + useIsMobile/useSwipe 훅 추가

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/hooks/useIsMobile.js

@@ -0,0 +1,18 @@
+import { useState, useEffect } from 'react';
+
+const MOBILE_BREAKPOINT = 768;
+
+export function useIsMobile() {
+  const [isMobile, setIsMobile] = useState(
+    () => window.matchMedia(`(max-width: ${MOBILE_BREAKPOINT}px)`).matches
+  );
+
+  useEffect(() => {
+    const mql = window.matchMedia(`(max-width: ${MOBILE_BREAKPOINT}px)`);
+    const handler = (e) => setIsMobile(e.matches);
+    mql.addEventListener('change', handler);
+    return () => mql.removeEventListener('change', handler);
+  }, []);
+
+  return isMobile;
+}