Update admin theme/layout and refresh README details.

Align the project baseline with the latest admin interface styling and layout structure while documenting setup and usage updates in README.

infra/k6/mvp-load-test.js

@@ -0,0 +1,20 @@
+import http from "k6/http";
+import { check, sleep } from "k6";
+
+export const options = {
+  stages: [
+    { duration: "1m", target: 10 },
+    { duration: "3m", target: 50 },
+    { duration: "1m", target: 0 }
+  ],
+  thresholds: {
+    http_req_duration: ["p(95)<300"],
+    http_req_failed: ["rate<0.01"]
+  }
+};
+
+export default function () {
+  const contentList = http.get("http://localhost:8000/api/v1/content/pages");
+  check(contentList, { "content list is 200": (r) => r.status === 200 });
+  sleep(1);
+}