fix(dev): vite stops watching what an e2e run writes

On Windows a report file being rewritten answered the watcher with EBUSY, which
took the dev server down, and each run reloaded every open page.

frontend/vite.config.ts

@@ -56,6 +56,12 @@ const watchEntry = (): Plugin => ({
 
 export default defineConfig({
   plugins: [reactWithCompiler(), devOnlyGuard(), chunkGuard(), watchEntry()],
-  server: { port: 5173, proxy },
+  server: {
+    port: 5173,
+    proxy,
+    // What an e2e run writes is no source. On Windows a file it is rewriting answers the watcher with
+    // EBUSY, which takes the whole dev server down; each run also reloaded every open page.
+    watch: { ignored: ["**/playwright-report/**", "**/test-results/**"] },
+  },
   build: { outDir: "dist", rollupOptions: { input: ["index.html", "watch.html"] } },
 });