fix: record browser startup failures (#4)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "hwacheon-network-viewer-validation",
   "private": true,
-  "scripts": { "test:ui": "node tests/viewer.cjs" },
+  "scripts": { "test:ui": "node tests/viewer.cjs", "test:runner": "node tests/launch-failure.cjs" },
   "devDependencies": { "playwright": "1.62.1" }
 }