K8s Environment Detection

https://kubernetes.io/docs/concepts/services-networking/service/#discovering-services

Example environment variables for an eks pod named eks-demo.

```
KUBERNETES_SERVICE_PORT: '443',
KUBERNETES_PORT: 'tcp://10.100.0.1:443',
EKS_DEMO_PORT_80_TCP_PORT: '80',
NODE_VERSION: '10.16.0',
HOSTNAME: 'eks-demo-55f57f865b-l7tcs',
EKS_DEMO_PORT_80_TCP_PROTO: 'tcp',
YARN_VERSION: '1.16.0',
SHLVL: '1',
HOME: '/root',
EKS_DEMO_PORT_80_TCP: 'tcp://10.100.122.110:80',
AWS_EMF_ENABLE_DEBUG_LOGGING: 'true',
KUBERNETES_PORT_443_TCP_ADDR: '10.100.0.1',
PATH:
'/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin',
AWS_EMF_AGENT_ENDPOINT: 'tcp://127.0.0.1:25888',
KUBERNETES_PORT_443_TCP_PORT: '443',
KUBERNETES_PORT_443_TCP_PROTO: 'tcp',
EKS_DEMO_SERVICE_HOST: '10.100.122.110',
KUBERNETES_PORT_443_TCP: 'tcp://10.100.0.1:443',
KUBERNETES_SERVICE_PORT_HTTPS: '443',
KUBERNETES_SERVICE_HOST: '10.100.0.1',
EKS_DEMO_SERVICE_PORT: '80',
EKS_DEMO_PORT: 'tcp://10.100.122.110:80',
PWD: '/app/src'
```

No source files or tests are named. Start with the linked Kubernetes service-discovery documentation and the sample EKS environment variables, then clarify which detection behavior and completion checks are expected.

Written by the indexing model from the issue text.