Update main page

src/app/page.tsx

@@ -0,0 +1,13 @@
+import RootLayout from './layout'
+import SignupPage from './signup/page'
+
+export default function Home() {
+  return (
+    <RootLayout>
+      <div style={{ display: 'flex', flexDirection: 'column', alignItems: 'center', justifyContent: 'center', height: '100vh' }}>
+        <h1 style={{ fontSize: 64, marginBottom: 20 }}>Welcome to Hoya</h1>
+        <SignupPage />
+      </div>
+    </RootLayout>
+  )
+}