Reorganize the help menu into one VIRTUAL MACHINES cluster covering all
backends, and bring docker/multipass/vbox to save+load parity:
- Launch-time dev toolchain: sandbox-bootstrap.sh + editable
sandbox-tools.json (vim/curl guaranteed), installed in docker AND
multipass sandboxes at provision time.
- Vbox load: vm_restore + `/sbx vmload <vm> [label]` (restore snapshot
then boot the GUI).
- Multipass load: `/sbx load` is now backend-aware (locate_snapshot +
SnapKind), mp_restore re-attaches the shared shell; teardown stops
(not purges) an instance that still has snapshots so they survive
`/sbx stop`.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
leetcrypt