goldenChat base source add

frontend/src/hooks/useMediaQuery.ts

@@ -0,0 +1,24 @@
+import { useEffect, useState } from 'react';
+
+/** CSS 미디어 쿼리 매칭 여부 (모바일·태블릿 분기용) */
+export function useMediaQuery(query: string): boolean {
+  const [matches, setMatches] = useState(() => {
+    if (typeof window === 'undefined') return false;
+    return window.matchMedia(query).matches;
+  });
+
+  useEffect(() => {
+    const mq = window.matchMedia(query);
+    const onChange = () => setMatches(mq.matches);
+    onChange();
+    mq.addEventListener('change', onChange);
+    return () => mq.removeEventListener('change', onChange);
+  }, [query]);
+
+  return matches;
+}
+
+/** 차트 메인 레이아웃 모바일 분기 (≤768px) */
+export function useIsMobile(): boolean {
+  return useMediaQuery('(max-width: 768px)');
+}