Add conditional MSW browser worker startup for E2E testing

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

package.json

@@ -5,12 +5,13 @@
   "scripts": {
     "dev": "vite",
     "build": "vite build",
+    "build:e2e": "VITE_MSW=true vite build",
     "preview": "vite preview",
     "test": "vitest",
     "coverage": "vitest run --coverage",
     "cy:run": "cypress run",
     "test:unit": "vitest --environment jsdom",
-    "test:e2e": "start-server-and-test preview :4173 'cypress run --e2e'",
+    "test:e2e": "start-server-and-test 'vite preview --port 4173' :4173 'cypress run --e2e'",
     "test:e2e:dev": "start-server-and-test 'vite dev --port 4173' :4173 'cypress open --e2e'",
     "lint": "eslint . --ext .vue,.js,.jsx,.cjs,.mjs",
     "lint:fix": "eslint . --ext .vue,.js,.jsx,.cjs,.mjs --fix",

src/main.ts

@@ -98,4 +98,14 @@ app.component("ContextMenu", ContextMenu);
 app.component("Draggable", draggable); // Drag and drop
 app.directive("tooltip", Tooltip);
 
-app.mount("#app");
+/**
+ * Starts the MSW service worker when VITE_MSW is set.
+ * Used for E2E testing with mock API responses.
+ */
+async function enableMocking() {
+  if (import.meta.env.VITE_MSW !== "true") return;
+  const { worker } = await import("./mocks/browser.js");
+  await worker.start({ onUnhandledRequest: "bypass" });
+}
+
+enableMocking().then(() => app.mount("#app"));