Connect: deploy openab-cp and view control plane status #1596

Problem

OpenAB Connect cannot deploy the control plane (openab-cp) and cannot show its status (registered workers, agents, delegations, health). Operators must use separate tooling for both.

Why now

Workflows will be persisted in openab-cp (see openabdev/openab-pty#77). Users need to see the control plane's state and whether it is running before creating workflows.

Requested behavior

(a) Connect can deploy or start an openab-cp instance from a configured target.
(b) Connect shows control plane status and the list of registered agents, using the existing read path cp/list_agents and the event stream cp/event.
(c) The first version may be a read-only status view.

Existing work

• feat(cp): observer/lobby — 3-phase design + Phase 1 protocol scaffold (PR 2/4) #1470 defines the read path. Its lobby UI was deferred.
• RFC: workflow orchestration over the control plane (Connect as primary, openab-pty hosts as workers) openab-pty#77 is the workflow dependency (RFC: workflow orchestration over the control plane).

Open questions

• Where deployment runs: local, remote host, or container.
• Who may deploy.
• Whether status is pull (poll) or push (cp/event).

Out of scope for this issue

The workflow scheduler (tracked in openabdev/openab-pty#77).