5c08701983
The last host-Docker dependency in the Firecracker launch path. Freeze and resume no longer touch the docker daemon, so the backend needs firecracker + KVM only — completing #348. Freeze: stream the guest rootfs over SSH straight into a persistent committed-rootfs.tar (the resumable/migratable artifact) instead of round-tripping through `docker build` from a scratch image. Written to a .partial sibling and atomically renamed so a failed freeze leaves no truncated artifact. Resume: extract the snapshot tar into a cached base dir and feed it to the existing rootless `mke2fs -d` pipeline, replacing the `docker create` + `docker export | tar` path. Recreate the proc/sys/dev/run mount points the freezer excludes so the guest init can mount them. `util.build_base_rootfs_dir` / `docker_image_id` stay — they still back the opt-in BOT_BOTTLE_INFRA_BUILD=local dev path and off-host publish_infra, which are out of scope. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01UoEZHDjv84ChoZbozQERhJ