Implemented a production-ready K3s Kubernetes installer with full lifecycle
support including installation, startup management, and cleanup.
Key features:
- Install first master (cluster init), join additional masters (HA), and workers
- Systemd service management via StartupManager abstraction
- IPv6 support with Mycelium interface auto-detection
- Robust destroy/cleanup with proper ordering to prevent hanging
- Complete removal of services, processes, network interfaces, and data
