Sessions show where their commands run and what they may touch
A session now has an explicit environment: where its commands run (compute) and what they may touch (containment).
In the UI: the session Workspace tab gains an Environment panel.
In the API: GET /v1/sessions/{id}/environment and
GET /v1/environment-targets are read-only views of the same data. The feature is
enabled wherever sandboxes are.
In code: the Framework’s Environment gains named compute and containment
members, with HostCompute behind the host-compute feature.