Add player leaderboard and homepage preview

app/leaderboard/loading.tsx

@@ -0,0 +1,24 @@
+export default function LoadingLeaderboard() {
+  return (
+    <main
+      className="section page-content leaderboard-page"
+      aria-busy="true"
+      aria-label="Loading leaderboard"
+    >
+      <span className="eyebrow">THE EXPLORERS’ BOARD</span>
+      <h1>Every block counts.</h1>
+      <p className="lead" role="status">
+        Fetching the explorers’ scores…
+      </p>
+      <div className="leaderboard-skeleton" aria-hidden="true">
+        {Array.from({ length: 6 }, (_, index) => (
+          <div key={index}>
+            <span />
+            <span />
+            <span />
+          </div>
+        ))}
+      </div>
+    </main>
+  );
+}