Runtime-, transport-, provider-, and database-neutral security contracts.
The crate turns Part 27's threat model into typed, fail-closed boundaries. Authentication
adapters establish [AuthenticationEvidence]; authoritative services consume only a
[ValidatedAuthContext]. External inputs pass explicit budgets, outbound destinations are
checked after DNS resolution, durable operation identities bind immutable semantics, and
security telemetry remains payload-free and low-cardinality.