feat(kiosk): forward kubernetes API port 6443 in install-vm for kc-agent connectivity

[castrojo]

Problem

When just install-vm or a local VM runs, only ports 8080 (kiosk console) and 2222 (ssh) are forwarded to the host. The local KubeStellar agent (kc-agent) running on the host requires access to the Kubernetes control plane API to inspect cluster state and bridge nodes/pods into the browser dashboard. Without forwarding 6443, kc-agent cannot reach the in-VM cluster API.

Fix

• Added hostfwd=tcp::6443-:6443 to the QEMU launch invocation in install-vm.