Implement Kubernetes provider

[dogancanbakir]

Description

Implement full Kubernetes provider (currently a stub).

Run code execution in Kubernetes pods for scalable, cloud-native workloads.

Requirements

• Connect to Kubernetes cluster (kubeconfig)
• Create pods with appropriate runtime images
• Execute code in pods
• Stream stdout/stderr via pod logs
• File system operations via kubectl cp
• Pod cleanup on stop
• Support for custom pod templates
• Resource limits (CPU, memory)

References

• Current stub: internal/provider/kubernetes/kubernetes.go
• client-go: https://github.com/kubernetes/client-go