The existing vbox paths only open pre-made images; there was no way to
build one from scratch. Add `/sbx launch vbox new [name]` backed by
scripts/vbox-new.sh: download an Ubuntu cloud image, convert it to a VDI,
build a cloud-init NoCloud seed that creates a sudo login user and installs
the sandbox-tools.json toolchain on first boot, then create + boot the VM.
VirtualBox guests can't be exec'd into like docker/multipass, so cloud-init
is the provisioning channel. Generates a one-time login password (or takes
--pass) and authorizes a local SSH key if present. Runs off-thread; rolls
back a half-built VM on failure.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
leetcrypt