New VMs should have mise available without a per-VM bootstrap step, and the activation needs to work in the default root bash workflow.
Install a pinned mise binary during both the Go-native image build path and the customize.sh rootfs rebuild path, then enable bash activation through /etc/profile.d for login shells and /etc/bash.bashrc for interactive shells.
Add a regression around the generated provisioning script and validate with bash -n customize.sh, go test ./..., and make build. Rebuilding the default rootfs is still required before future default-image VMs pick up the change.
