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Add an abstract teardown() classmethod to BottleBackend — the inverse of setup(), surfaced as `./cli.py backend teardown [--backend=NAME]` (uninstall). Symmetric with setup: it prints the privileged commands / declarative config change to remove the host prerequisites. - firecracker: NixOS-aware — disable the flake module (or drop the import) and rebuild, or `firecracker-netpool.sh down` imperatively. - docker / macos-container: nothing to undo (no privileged host state); print a short note. Not called by the launch path or the test suite. Extends test_cli_backend for the new dispatch. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck