feat(e2e): consolidate E2E test infrastructure + add waitForSidebar (PRI-698)

- Adds e2e/auth.setup.ts, e2e/tns-csi.spec.ts with waitForSidebar helper
- Adds playwright.config.ts, scripts/deploy-e2e-headlamp.sh, scripts/teardown-e2e-headlamp.sh
- Adds .github/workflows/e2e.yaml
- Plugin settings test waits for list before searching

scripts/teardown-e2e-headlamp.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+REPO_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+
+E2E_NAMESPACE="${E2E_NAMESPACE:-headlamp-dev}"
+E2E_RELEASE="${E2E_RELEASE:-headlamp-e2e}"
+
+echo "=== E2E Headlamp Teardown ==="
+echo "  Namespace: $E2E_NAMESPACE"
+echo "  Release:   $E2E_RELEASE"
+
+echo "Removing Headlamp Deployment, Service, and ServiceAccount..."
+kubectl delete deployment "${E2E_RELEASE}" -n "$E2E_NAMESPACE" --ignore-not-found
+kubectl delete service "${E2E_RELEASE}" -n "$E2E_NAMESPACE" --ignore-not-found
+kubectl delete serviceaccount "${E2E_RELEASE}" -n "$E2E_NAMESPACE" --ignore-not-found
+
+echo "Cleaning up ConfigMap..."
+kubectl delete configmap headlamp-tns-csi-plugin -n "$E2E_NAMESPACE" --ignore-not-found
+
+echo "Cleaning up test service account..."
+kubectl delete serviceaccount headlamp-e2e-test -n "$E2E_NAMESPACE" --ignore-not-found
+
+if [ -f "$REPO_ROOT/.env.e2e" ]; then
+  rm "$REPO_ROOT/.env.e2e"
+  echo "Removed .env.e2e"
+fi
+
+echo ""
+echo "E2E teardown complete."