Before this change smolmachines prepare.py spliced bottle.env directly
into guest_env, so ?prompt and ${HOST_VAR} entries reached the VM as
raw sentinels rather than being prompted or interpolated.
After this change prepare.py calls resolve_env(), matching the Docker
backend's contract. Forwarded (secret/interpolated) values still flow
through smolvm -e K=V argv — the known exposure gap documented in PRD
0038's open question.
Closes#135
didericis-claude