//! Application layer — use cases and registries.
//!
//! Holds:
//! - [`spec_registry`] — Specification registry (dynamic / composable selector)
//! - [`projection_registry`] — NamedProjection registry (fixed / named view)
//! - [`use_cases`] — wire_init / wire_close / wire_doctor / etc. flows
//! - [`auth`] — indirect authentication reference layer
//! (`AuthSpec` / `AuthResolver`) consumed by adapter fetches via the
//! `?auth=<service_key>` URI query param convention