Rebuild on the Bennett platform: Spring Boot + Vite/React

Same site — glass header, bento grid, hero drift, dark mode — with three things fixed
on the way:

- Tailwind and lucide came from CDNs on every page load, and the fonts from Google. All
  are now built in or self-hosted, so the site owes nothing to third parties at runtime.
- The hero and bento photographs were hot-linked from Unsplash. They are re-encoded to
  webp and served from the MinIO bucket with a year-long cache.
- The ministries and labs were hard-coded in the markup, so launching a ministry meant
  editing HTML. They now come from /api/network.

The mobile menu button also opens something now; it did nothing before.

frontend/src/main.tsx

@@ -0,0 +1,17 @@
+import { StrictMode } from 'react';
+import { createRoot } from 'react-dom/client';
+import App from './App';
+import './index.css';
+
+// Respect the reader's saved choice, then the system, before first paint of the app.
+const saved = localStorage.getItem('rwn-theme');
+const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
+if (saved === 'dark' || (!saved && prefersDark)) {
+  document.documentElement.classList.add('dark');
+}
+
+createRoot(document.getElementById('root')!).render(
+  <StrictMode>
+    <App />
+  </StrictMode>,
+);