Add visitor tracking and combat selection features

src/ui/visitorCounter.js

@@ -0,0 +1,23 @@
+export async function trackVisitor({ onUpdate, onError } = {}) {
+  try {
+    const response = await fetch("/api/visitors/check", {
+      method: "POST",
+      headers: {
+        Accept: "application/json",
+        "Content-Type": "application/json",
+      },
+      body: "{}",
+    });
+
+    if (!response.ok) {
+      throw new Error(`Visitor check failed: ${response.status}`);
+    }
+
+    const visitorStats = await response.json();
+    onUpdate?.(visitorStats);
+    return visitorStats;
+  } catch (error) {
+    onError?.(error);
+    return null;
+  }
+}