fix: Show skeleton instead of sample images during banner loading

Sample car images (Tesla, Sportage etc.) now only appear as fallback
when the API fails to respond within 3 seconds. During normal loading,
a pulse-animated skeleton is shown instead.

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

frontend/src/app/page.tsx

@@ -12,8 +12,18 @@ export default function Home() {
   const { t, language } = useTranslation();
   const [banners, setBanners] = useState<HeroBanner[]>([]);
   const [bannerSettings, setBannerSettings] = useState<HeroBannerSettings | undefined>();
+  const [bannerLoaded, setBannerLoaded] = useState(false);
+  const [showFallback, setShowFallback] = useState(false);
 
   useEffect(() => {
+    setBannerLoaded(false);
+    setShowFallback(false);
+
+    // 3초 후에도 로딩 안 되면 샘플 배너 표시
+    const fallbackTimer = setTimeout(() => {
+      setShowFallback(true);
+    }, 3000);
+
     const loadBanners = async () => {
       try {
         const [bannersData, settingsData] = await Promise.all([
@@ -24,10 +34,15 @@ export default function Home() {
         setBannerSettings(settingsData);
       } catch (error) {
         console.error('Failed to load banners:', error);
-        // 에러 시 샘플 배너 사용 (FilmStripSlider 내부에서 처리)
+        setShowFallback(true);
+      } finally {
+        setBannerLoaded(true);
+        clearTimeout(fallbackTimer);
       }
     };
     loadBanners();
+
+    return () => clearTimeout(fallbackTimer);
   }, [language]);
 
   return (
@@ -44,7 +59,11 @@ export default function Home() {
         </div>
 
         {/* Film Strip Slider */}
-        <FilmStripSlider banners={banners} settings={bannerSettings} />
+        <FilmStripSlider
+          banners={banners}
+          settings={bannerSettings}
+          loading={!bannerLoaded && !showFallback}
+        />
 
         <div className="container mx-auto px-4 py-4 sm:py-8">
           <div className="flex flex-col lg:flex-row items-center gap-4 lg:gap-6">

frontend/src/components/FilmStripSlider.tsx

@@ -10,6 +10,7 @@ import { useLanguageStore, Language, translateCarName } from '@/lib/i18n';
 interface FilmStripSliderProps {
   banners: HeroBanner[];
   settings?: HeroBannerSettings;
+  loading?: boolean;
 }
 
 // 기본 설정
@@ -124,9 +125,11 @@ const sampleBanners: HeroBanner[] = [
   },
 ];
 
-export default function FilmStripSlider({ banners, settings }: FilmStripSliderProps) {
+export default function FilmStripSlider({ banners, settings, loading }: FilmStripSliderProps) {
   const effectiveSettings = settings || defaultSettings;
-  const effectiveBanners = banners.length > 0 ? banners : sampleBanners;
+  // 로딩 중이면 빈 배열 사용 → 스켈레톤 표시
+  // 로딩 완료 후 데이터 없으면 sampleBanners (3초 이상 미응답 시에만 도달)
+  const effectiveBanners = loading ? [] : (banners.length > 0 ? banners : sampleBanners);
 
   // 무한 루프를 위해 배너를 3배로 복제
   const duplicatedBanners = [...effectiveBanners, ...effectiveBanners, ...effectiveBanners];
@@ -285,6 +288,37 @@ export default function FilmStripSlider({ banners, settings }: FilmStripSliderPr
     }
   };
 
+  // 로딩 중이면 스켈레톤 표시
+  if (loading || effectiveBanners.length === 0) {
+    return (
+      <div className="relative w-full overflow-hidden bg-gradient-to-b from-gray-900 to-gray-800 py-4 sm:py-8">
+        <div className="absolute top-0 left-0 right-0 h-3 sm:h-4 bg-gray-900 hidden sm:flex items-center justify-around">
+          {Array.from({ length: 30 }).map((_, i) => (
+            <div key={i} className="w-2 sm:w-3 h-1.5 sm:h-2 bg-gray-700 rounded-sm" />
+          ))}
+        </div>
+        <div className="relative overflow-hidden mx-auto" style={{ height: imageHeight + 20 }}>
+          <div className="flex absolute" style={{ paddingLeft: gap, gap: gap }}>
+            {Array.from({ length: 5 }).map((_, i) => (
+              <div
+                key={i}
+                className="flex-shrink-0 rounded-lg overflow-hidden bg-gray-700 animate-pulse"
+                style={{ width: imageWidth, height: imageHeight }}
+              />
+            ))}
+          </div>
+        </div>
+        <div className="absolute bottom-0 left-0 right-0 h-3 sm:h-4 bg-gray-900 hidden sm:flex items-center justify-around">
+          {Array.from({ length: 30 }).map((_, i) => (
+            <div key={i} className="w-2 sm:w-3 h-1.5 sm:h-2 bg-gray-700 rounded-sm" />
+          ))}
+        </div>
+        <div className="absolute top-0 sm:top-4 bottom-0 sm:bottom-4 left-0 w-8 sm:w-24 bg-gradient-to-r from-gray-900 to-transparent pointer-events-none z-10" />
+        <div className="absolute top-0 sm:top-4 bottom-0 sm:bottom-4 right-0 w-8 sm:w-24 bg-gradient-to-l from-gray-900 to-transparent pointer-events-none z-10" />
+      </div>
+    );
+  }
+
   return (
     <div className="relative w-full overflow-hidden bg-gradient-to-b from-gray-900 to-gray-800 py-4 sm:py-8">
       {/* Film strip effect - top perforation (hidden on very small screens) */}