fix: correct main.ts import reference

Fixed undefined SimpleApp reference to use App component.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: Seungwoo321

src/main.ts

@@ -1,6 +1,6 @@
 import { createApp } from 'vue'
 import App from './App.vue'
 
-const app = createApp(SimpleApp)
+const app = createApp(App)
 
 app.mount('#app')