Keep the minimal sandbox command's existing app/data identity while sharing
its parser, seeding, execution and cleanup with the standard sandbox.
Remove the unused SDK adapter copy and protocol shadow from the environment
facade, plus unconsumed checkout-updater dependencies and their dead helper.
Validation: 72 focused Python tests across sandbox and adapter/backend
paths, 5 checkout-updater tests, Electron typecheck and ESLint passed.
Ruff, touched-file Windows checks and the TS ratchet pass. Sandbox tests
also passed against the original scripts before consolidation.
