Manifest now holds exactly one agent and one effective bottle (with
git_user overlay already applied). The old multi-agent/bottle
collection is renamed ManifestIndex. BottleSpec.manifest starts as
ManifestIndex from the CLI and becomes Manifest after _validate()
calls load_for_agent(); all provisioning code downstream reads
spec.manifest.agent / spec.manifest.bottle instead of indexing by name.
Both docker and smolmachines backends use bottle state helpers.
Moving to bot_bottle/ makes the sharing explicit and removes the
cross-backend dependency (smolmachines importing from ..docker).
All callers updated: docker backend, smolmachines backend, cli
modules, and tests.
BottleMetadata gains a backend field (default ""). Docker prepare writes
"docker"; smolmachines prepare writes "smolmachines". read_metadata
deserialises it with "" as the backward-compatible default.
resume now passes metadata.backend to _launch_bottle so a preserved
smolmachines bottle is resumed on the right backend without requiring
BOT_BOTTLE_BACKEND to be set manually.
_bottle_for_slug now reads metadata.backend and constructs a
SmolmachinesBottle for smolmachines slugs instead of always defaulting
to DockerBottle. No-metadata slugs still fall back to Docker.
Closes#137
didericis-claude
didericis-codex