Fix EKS Worker Nodes Not Joining the Cluster

EC2 instances are running and healthy, but `kubectl get nodes` doesn't show them.

• Node IAM role missing from the `aws-auth` ConfigMap.
• Node role lacks AmazonEKSWorkerNodePolicy or AmazonEC2ContainerRegistryReadOnly.
• Security groups don't allow node ↔ control plane traffic on 443.
• User-data bootstrap script never ran (wrong AMI or missing args).

Patch aws-auth

apiVersion: v1
kind: ConfigMap
metadata:
  name: aws-auth
  namespace: kube-system
data:
  mapRoles: |
    - rolearn: arn:aws:iam::123:role/eks-node-role
      username: system:node:{{EC2PrivateDNSName}}
      groups:
        - system:bootstrappers
        - system:nodes

Verify on the node

sudo journalctl -u kubelet -n 100 --no-pager