Add E2E test infrastructure for kube-vip plugin

Scaffolded via e2e-scaffold.sh (proactive improvement).
- playwright.config.ts, e2e/auth.setup.ts, e2e/kube-vip.spec.ts
- scripts/deploy-e2e-headlamp.sh, scripts/teardown-e2e-headlamp.sh
- .github/workflows/e2e.yaml uses reusable workflow
- @playwright/test ^1.58.2 devDep

- PRI-641

Co-Authored-By: Paperclip <noreply@paperclip.ing>

package.json

@@ -23,7 +23,9 @@
     "format": "prettier --write src/",
     "format:check": "prettier --check src/",
     "test": "vitest run",
-    "test:watch": "vitest"
+    "test:watch": "vitest",
+    "e2e": "playwright test",
+    "e2e:headed": "playwright test --headed"
   },
   "peerDependencies": {
     "react": "^18.0.0",
@@ -52,6 +54,7 @@
     "react-dom": "^18.3.1",
     "react-router-dom": "^5.3.0",
     "typescript": "~5.6.2",
-    "vitest": "^3.2.4"
+    "vitest": "^3.2.4",
+    "@playwright/test": "^1.58.2"
   }
 }