style: change 'Voir les lots' button to green on homepage

- Update button color from orange to green (#1a4d2e)
- Add hover effect to darker green (#2d5a3d)
- 'Participer maintenant' stays orange for CTA emphasis

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/page.tsx

@@ -37,7 +37,7 @@ export default function HomePage() {
                 </button>
               </Link>
               <Link href="/lots">
-                <button className="bg-[#f59e0b] hover:bg-[#d97706] text-white font-bold text-lg px-10 py-4 rounded-lg shadow-xl transition-all w-full sm:w-auto">
+                <button className="bg-[#1a4d2e] hover:bg-[#2d5a3d] text-white font-bold text-lg px-10 py-4 rounded-lg shadow-xl transition-all w-full sm:w-auto">
                   Voir les lots
                 </button>
               </Link>