Migrate Cypress E2E from cy.intercept to MSW service worker

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

cypress/e2e/navigation.cy.js

@@ -21,7 +21,7 @@ describe("Navigation and Routing", () => {
   it("navbar shows correct view name", () => {
     loginWithFixtures();
     cy.visit("/files");
-    cy.wait("@getFiles");
+    cy.contains("sample-process.xes").should("exist");
     cy.get("#nav_bar").should("exist");
     cy.get("#nav_bar h2").should("contain", "FILES");
   });