Migrate Cypress E2E from cy.intercept to MSW service worker

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cypress/e2e/accountAdmin/createAccount.cy.js

@@ -9,13 +9,22 @@ import { loginWithFixtures } from "../../support/intercept";
 describe("Create an Account", () => {
   beforeEach(() => {
     loginWithFixtures();
-    // Override: new usernames should return 404 (account doesn't exist yet)
-    cy.intercept("GET", "/api/users/unit-test-*", {
-      statusCode: 404,
-      body: { detail: "Not found" },
-    }).as("checkNewUser");
     cy.visit("/account-admin");
-    cy.wait("@getUsers");
+    cy.contains("Test Admin").should("exist");
+    // Override: new usernames should return 404 (account doesn't exist yet)
+    cy.window().then((win) => {
+      const { http, HttpResponse } = win.__msw__;
+      win.__mswWorker__.use(
+        http.get("/api/users/:username", ({ params }) => {
+          if (params.username.startsWith("unit-test-")) {
+            return HttpResponse.json(
+              { detail: "Not found" },
+              { status: 404 },
+            );
+          }
+        }),
+      );
+    });
   });
 
   it("Create a new account with admin role; should show saved message.", () => {
@@ -30,7 +39,6 @@ describe("Create an Account", () => {
       .should("be.visible")
       .and("be.enabled")
       .click();
-    cy.wait("@postUser");
     cy.contains("Account added").should("be.visible");
   });