Phase 4.7 — pure-Java contract module shared between juke-remix-rest-service and every plugin. Contains the PluginCapability enum, registration DTOs, per-capability request/response DTOs, and the error envelope. No Spring annotations on any class — the whole point is that plugins written against any framework (or no framework at all) can depend on this module without dragging in Spring.

Phase 4.7 — Spring Boot starter plugins depend on. Provides: * @PluginCapability and @PluginEndpoint annotations, * RegistrationLifecycleBean (handshake on ApplicationReadyEvent), * HeartbeatPublisher (@Scheduled), ...

Juke agent — Community-clean record/replay/session REST surface and plugin registration relay