feat: Vite + React 19 + Tailwind + TypeScript scaffold

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

frontend/src/App.tsx

@@ -0,0 +1,7 @@
+export default function App() {
+  return (
+    <div className="min-h-screen flex items-center justify-center" style={{background:'var(--bg-root)', color:'var(--text)'}}>
+      <h1 className="text-2xl font-bold">Hive Manage v3</h1>
+    </div>
+  )
+}

frontend/src/main.tsx

@@ -0,0 +1,7 @@
+import React from 'react'
+import ReactDOM from 'react-dom/client'
+import App from './App'
+
+ReactDOM.createRoot(document.getElementById('root')!).render(
+  <React.StrictMode><App /></React.StrictMode>
+)