Refactor AdminPage and remove AdminPanel component: Simplify admin navigation by redirecting to preferences page and eliminating the AdminPanel component, streamlining the admin interface.

components/admin/AdminNavigation.tsx

@@ -0,0 +1,41 @@
+"use client";
+
+import Link from "next/link";
+import { usePathname } from "next/navigation";
+import { Button } from "@/components/ui";
+
+const adminSections = [
+  { id: "preferences", label: "Préférences UI", path: "/admin/preferences" },
+  { id: "users", label: "Utilisateurs", path: "/admin/users" },
+  { id: "events", label: "Événements", path: "/admin/events" },
+  { id: "feedbacks", label: "Feedbacks", path: "/admin/feedbacks" },
+  { id: "challenges", label: "Défis", path: "/admin/challenges" },
+  { id: "houses", label: "Maisons", path: "/admin/houses" },
+];
+
+export default function AdminNavigation() {
+  const pathname = usePathname();
+
+  return (
+    <div className="flex gap-4 mb-8 justify-center flex-wrap">
+      {adminSections.map((section) => {
+        const isActive = pathname === section.path || 
+          (section.path === "/admin/preferences" && pathname === "/admin");
+        
+        return (
+          <Button
+            key={section.id}
+            as={Link}
+            href={section.path}
+            variant={isActive ? "primary" : "secondary"}
+            size="md"
+            className={isActive ? "bg-pixel-gold/10" : ""}
+          >
+            {section.label}
+          </Button>
+        );
+      })}
+    </div>
+  );
+}
+