## Why
`allowedWindowsSandboxImplementations` uses the legacy setup-mode type, which cannot represent `mxc`.
## What changed
- Introduce `WindowsSandboxImplementation` with `elevated`, `unelevated`, and `mxc` variants for configuration requirements, and update the generated schemas and TypeScript and Python types.
- Keep `WindowsSandboxSetupMode` limited to `elevated` and `unelevated`, and update the requirements mapping and its test assertions to use the new type.
- Document that clients selecting `mxc` skip the legacy setup and readiness APIs and use the standard `command/exec` streaming and process-control path.
GitOrigin-RevId: c926e853f0bbdb29d4b437866c284c1394a7ea13
iceweasel-oai
fbad00774b