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/SectionHeading.js

@@ -0,0 +1,14 @@
+import Reveal from './Reveal';
+
+export default function SectionHeading({ index, eyebrow, title, children }) {
+  return (
+    <Reveal className="section-heading">
+      <p className="eyebrow">
+        <span className="eyebrow-index">{index}</span>
+        {eyebrow}
+      </p>
+      <h2 className="section-title">{title}</h2>
+      {children && <p className="section-lead">{children}</p>}
+    </Reveal>
+  );
+}