bug(server): driver-initiated stops report Error instead of Stopped #4638

Problem

The gateway maps a Ready=False condition with reason ContainerStopped to the Stopped phase only when the gateway itself requested the stop. When the driver stops a sandbox on its own (for example, stopping VMs it cannot relaunch during recovery after a driver restart), the sandbox shows Error, and openshell sandbox start refuses to start it.

Today

External drivers add a Suspended=True condition, borrowed from the Kubernetes driver, which the gateway maps to Stopped.

Proposal

Treat ContainerStopped as Stopped regardless of who initiated the stop, or document the Suspended convention as part of the driver contract.