feat(aws): complete the EKS adapter (nodegroup/fargate management)

[hectorvent]

Complete the AWS EKS adapter

EKS is already registered under the k8s type but only lists/inspects clusters. Add management of
nodegroups and Fargate profiles (the legacy routes/eks.ts already exposes these — reuse or port).

• Nodegroup create / delete in packages/api/src/adapter-aws/AwsK8sAdapter.ts (+ test)
• Fargate profile create / delete
• Wire actions into the schema and the K8sEngineDetails panel (packages/frontend/src/components/)
• Verify against the local emulator (floci/src/main/java/io/github/hectorvent/floci/services/eks/)