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>

components/ThemeToggle.js

@@ -0,0 +1,30 @@
+import { useEffect, useState } from 'react';
+import Icon from './Icon';
+
+export default function ThemeToggle() {
+  const [theme, setTheme] = useState(null);
+
+  useEffect(() => {
+    setTheme(document.documentElement.dataset.theme || 'light');
+  }, []);
+
+  const toggle = () => {
+    const next = theme === 'dark' ? 'light' : 'dark';
+    document.documentElement.dataset.theme = next;
+    try {
+      localStorage.setItem('theme', next);
+    } catch (e) {}
+    setTheme(next);
+  };
+
+  return (
+    <button
+      type="button"
+      className="icon-button"
+      onClick={toggle}
+      aria-label={`Switch to ${theme === 'dark' ? 'light' : 'dark'} theme`}
+    >
+      <Icon name={theme === 'dark' ? 'sun' : 'moon'} />
+    </button>
+  );
+}