Add OcspChainValidationEvent DTO, OcspStatus enum, and OcspEventBuilder
helper with BuildPeerReject, BuildChainValidation, and ParseStatus methods.
Register OcspChainValidationEvent in EventJsonContext source-gen context.
Add OcspPeerReject and OcspChainValidation subject constants to EventSubjects.
10 new tests in OcspEventTests cover all DTOs, builder methods, status
parsing, and JSON round-trip.
Add RemoteServerShutdownEvent, RemoteServerUpdateEvent, LeafNodeConnectEvent,
and LeafNodeDisconnectEvent types plus matching EventSubjects constants, with
10 unit tests covering type identity, field assignment, format placeholders,
and JSON roundtrip serialization.
Add JetStream advisory subject constants to EventSubjects and a lightweight
AdvisoryPublisher that publishes stream/consumer lifecycle events to
$JS.EVENT.ADVISORY.* subjects without depending on InternalEventSystem
directly (testable via Action delegate injection).
