Simplify hook runtime state

Remove the unused pending-hook layer and dead protocol trait wrappers, and resolve active hooks through a direct active-only flow with peer-side indexing instead of scan-based recovery.

src/lib.rs

@@ -1,12 +1,11 @@
 //! # UnShell Core
 //!
 //! This crate implements the UnShell protocol as a pure, `no_std` library.
-//! It provides a trait-based architecture for routed endpoint communication
-//! using an explicit tree topology.
+//! It provides routed endpoint communication using an explicit tree topology.
 //!
 //! ## Architecture
 //!
-//! - [`protocol`] - Wire types, framing, stateless validation, routing/runtime, and implementation traits.
+//! - [`protocol`] - Wire types, framing, stateless validation, and routing/runtime.
 //!
 //! The library requires `alloc` for path and payload management.