implement challenge verification flow with altcha integration and add challenge page

containers/auth-gateway/auth_gateway/static/challenge.js

@@ -0,0 +1,35 @@
+document.addEventListener("DOMContentLoaded", function () {
+    var widget = document.getElementById("altcha-widget");
+    var progressFill = document.getElementById("progress-fill");
+    var statusText = document.getElementById("challenge-status");
+    var challengeIcon = document.getElementById("challenge-icon");
+
+    if (!widget) return;
+
+    var fakeProgress = 0;
+    var progressInterval = setInterval(function () {
+        fakeProgress = Math.min(fakeProgress + Math.random() * 2.5, 88);
+        progressFill.style.width = fakeProgress + "%";
+    }, 150);
+
+    widget.addEventListener("statechange", function (ev) {
+        if (ev.detail.state === "verified") {
+            clearInterval(progressInterval);
+            progressFill.style.width = "100%";
+            progressFill.classList.add("progress-done");
+            challengeIcon.textContent = "✓";
+            challengeIcon.classList.add("challenge-icon-done");
+            statusText.textContent = "Verification complete. Redirecting...";
+            document.getElementById("altcha-payload").value = ev.detail.payload;
+            setTimeout(function () {
+                document.getElementById("challenge-form").submit();
+            }, 500);
+        } else if (ev.detail.state === "error") {
+            clearInterval(progressInterval);
+            challengeIcon.textContent = "✕";
+            challengeIcon.classList.add("challenge-icon-error");
+            statusText.textContent = "Verification failed. Please reload the page.";
+            progressFill.classList.add("progress-error");
+        }
+    });
+});