feat: redesign site as a modern developer portfolio

- New home page: hero, stats, about, focus areas, stack, projects, contact
- Light/dark theme with system default and persisted toggle
- Content centralised in data/profile.js
- Restyle /rates to match; remove it from nav and projects
- Afriex: log a clear error now that its API requires a device id

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

pages/_document.js

@@ -0,0 +1,19 @@
+import { Html, Head, Main, NextScript } from 'next/document';
+
+// Set the theme before first paint to avoid a light/dark flash.
+const themeScript = `(function(){try{var t=localStorage.getItem('theme');if(!t){t=window.matchMedia('(prefers-color-scheme: dark)').matches?'dark':'light'}document.documentElement.dataset.theme=t}catch(e){}})();`;
+
+export default function Document() {
+  return (
+    <Html lang="en">
+      <Head>
+        <link rel="preload" href="/fonts/inter_font.ttf" as="font" type="font/ttf" crossOrigin="anonymous" />
+        <script dangerouslySetInnerHTML={{ __html: themeScript }} />
+      </Head>
+      <body>
+        <Main />
+        <NextScript />
+      </body>
+    </Html>
+  );
+}