fix(e2e): use NodePort instead of cluster-internal DNS for HEADLAMP_URL

Previous attempt used kubectl port-forward to a Service, which failed
with 'connection refused' — the API server could not reach pod IPs.

Switch to NodePort (30080) service type and use the node's InternalIP
for HEADLAMP_URL, reachable from the GitHub Actions runner pod.

- Change Service type from ClusterIP to NodePort with nodePort: 30080
- After rollout, get node InternalIP via kubectl get nodes
- Poll http://<node-ip>:30080 until reachable
- Write HEADLAMP_URL=http://<node-ip>:30080 to .env.e2e
- Remove port-forward leftover cleanup from teardown script

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

scripts/teardown-e2e-headlamp.sh

@@ -22,14 +22,9 @@ 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"
+  rm -f "$REPO_ROOT/.env.e2e"
   echo "Removed .env.e2e"
 fi
 
-echo "Killing any kubectl port-forward processes for ${E2E_RELEASE}..."
-pkill -f "kubectl port-forward.*${E2E_RELEASE}" 2>/dev/null || true
-
-rm -f "$REPO_ROOT/.port-forward.log"
-
 echo ""
 echo "E2E teardown complete."