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.
When a label is set (e.g. "bob"), the display becomes "bob (claude-implementer)"
so the agent type is always visible. Affects all three backends (docker,
macos-container, smolmachines) and the `cli.py list active` output.
Closes#243
didericis-claude
didericis
didericis-codex