ControlPlane

Entry point for reporting a self-deployed agent to the controlplane control plane.

Full instrumentation, including the Level-2 event stream, needs the observer middleware registered while the agent is being built, because a ReActAgent's middleware list is fixed at construction:

`AgentScopeAdapter adapter = new AgentScopeAdapter();
ReActAgent agent = ReActAgent.builder()
.name("Friday")
.model(model)
.middleware(adapter.middleware())
.build();

SessionBridge bridge = ControlPlane.instrument(agent,
ControlPlaneConfig.builder("my-agentscope-agent")
.controlPlaneHttp("http://localhost:8081")
.internalToken(System.getenv("BUILDER_INTERNAL_TOKEN"))
.namespace("default")
.enableEvents(true)
.contractHttpPort(18090)
.build(),
adapter);
`

#instrument(Object, ControlPlaneConfig) also works on an agent that is already built. It reports session snapshots, effective context, history and commands — everything that reads live state — but emits no events, since there is no way to add a middleware after construction.

The returned bridge is AutoCloseable; close it to detach and release both channels.