feat: add Vite entry point and root App component

src/App.tsx

@@ -0,0 +1,69 @@
+import { css } from '@emotion/react';
+import { useEffect } from 'react';
+import { BottomTabBar } from './components/BottomTabBar';
+import { OfflineRewardModal } from './components/OfflineRewardModal';
+import { AchievementToast } from './components/AchievementToast';
+import { ElementsScreen } from './components/screens/ElementsScreen';
+import { EvolutionScreen } from './components/screens/EvolutionScreen';
+import { FusionScreen } from './components/screens/FusionScreen';
+import { ShopScreen } from './components/screens/ShopScreen';
+import { AchievementsScreen } from './components/screens/AchievementsScreen';
+import { SettingsScreen } from './components/screens/SettingsScreen';
+import { TutorialOverlay } from './components/tutorial/TutorialOverlay';
+import { useIdleTick } from './hooks/useIdleTick';
+import { useGameStore } from './store/useGameStore';
+import { trackGameEvent } from './platform/analytics';
+
+const rootStyle = css`
+  width: 100%;
+  height: 100vh;
+  display: flex;
+  flex-direction: column;
+  background-color: #f7f8fa;
+  overflow: hidden;
+  font-family:
+    'Pretendard',
+    -apple-system,
+    BlinkMacSystemFont,
+    sans-serif;
+`;
+
+const contentStyle = css`
+  flex: 1;
+  overflow-y: auto;
+  padding-bottom: 72px;
+`;
+
+export function App() {
+  const { activeTab, setActiveTab, elements, gold, elementLevels } = useGameStore();
+  useIdleTick();
+
+  useEffect(() => {
+    const ownedCount = Object.values(elements).filter((c) => c > 0).length;
+    const totalLevel = Object.values(elementLevels).reduce((sum, lv) => sum + lv, 0);
+    trackGameEvent('app_open', {
+      platform: 'web',
+      platform_time: new Date().toISOString(),
+      owned_element_count: ownedCount,
+      gold,
+      total_enhance_level: totalLevel,
+    });
+  }, []);
+
+  return (
+    <div css={rootStyle}>
+      <OfflineRewardModal />
+      <AchievementToast />
+      <div css={contentStyle}>
+        {activeTab === 'elements' && <ElementsScreen />}
+        {activeTab === 'evolution' && <EvolutionScreen />}
+        {activeTab === 'fusion' && <FusionScreen />}
+        {activeTab === 'shop' && <ShopScreen />}
+        {activeTab === 'achievements' && <AchievementsScreen />}
+        {activeTab === 'settings' && <SettingsScreen />}
+      </div>
+      <BottomTabBar activeTab={activeTab} onTabChange={setActiveTab} />
+      <TutorialOverlay />
+    </div>
+  );
+}

src/main.tsx

@@ -0,0 +1,23 @@
+import { StrictMode } from 'react';
+import { createRoot } from 'react-dom/client';
+import { App } from './App';
+import { initAnalytics } from './platform/analytics';
+import { useGameStore, flushGameState } from './store/useGameStore';
+
+initAnalytics();
+
+// 탭 종료/이탈 시 즉시 저장 (throttledStorage 보호)
+window.addEventListener('beforeunload', flushGameState);
+window.addEventListener('pagehide', flushGameState);
+
+// 첫 진입 시 오프라인 보상 계산
+useGameStore.getState().initOffline();
+
+const rootEl = document.getElementById('root');
+if (!rootEl) throw new Error('Root element #root not found in index.html');
+
+createRoot(rootEl).render(
+  <StrictMode>
+    <App />
+  </StrictMode>
+);