refactor: migrate contact form to TanStack Form

- Replace manual state management with @tanstack/react-form
- Add proper Field/FieldLabel components for accessibility
- Simplify server action (remove useActionState signature)
- Remove use-debounce dependency
- Update PGP key links and minor styling tweaks

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/projects/page.tsx

@@ -73,7 +73,7 @@ const Page = async () => {
                 href={repo!.url}
                 target="_blank"
                 rel="noopener noreferrer"
-                className="inline-block text-base leading-relaxed font-semibold"
+                className="inline-block text-base leading-relaxed font-semibold text-[#0969da] hover:underline dark:text-[#4493f8]"
               >
                 {repo!.name}
               </a>