Initial setup: Korean community aggregator web app

- Set up Vite + React + TypeScript project
- Configure Tailwind CSS v4 with PostCSS
- Create project structure (components, types, data)
- Implement core features:
  - Header with search functionality
  - PostCard component for displaying posts
  - PostList with community filtering (전체/디씨/루리웹/아카)
  - PostModal for detailed post view
- Add mock data for 3 communities (DCInside, Ruliweb, Arcalive)
- Update README with project documentation

src/App.tsx

@@ -0,0 +1,19 @@
+import { useState } from 'react';
+import Header from './components/common/Header';
+import PostList from './components/PostList';
+import mockPosts from './data/mock-posts.json';
+import type { Post } from './types';
+
+function App() {
+  const [searchQuery, setSearchQuery] = useState('');
+  const posts = mockPosts as Post[];
+
+  return (
+    <div className="min-h-screen bg-gray-50">
+      <Header onSearch={setSearchQuery} />
+      <PostList posts={posts} searchQuery={searchQuery} />
+    </div>
+  );
+}
+
+export default App;