V00.75 SPI core for the Security Event Bus: sealed SecurityEvent hierarchy, signed SecurityEventEnvelope, EventBus API, Publish/Consume pipelines, and the SPI surfaces for SignatureAlgorithm, PayloadCodec, KeyManagement, ReplayStore, SequenceStore, ProducerPolicy, EventStore, DeadLetterStore. Framework-neutral — no Vaadin, no REST framework, no Eclipse Store. Persistent stores and the REST/SSE bridge ship in the jCustos Enterprise edition.