//! LocalInterface — shared-instance control socket (`ARCHITECTURE.md` §4.4).
//!
//! Lets separate processes on the same host share one daemon. **Blocks
//! adoption** without it (Sideband/MeshChat/NomadNet rely on it).
//!
//! We diverge from the reference (§4.4): a Unix domain socket with
//! length-prefixed messages and capability tokens, plus a Reticulum-compatible
//! TCP-on-loopback shim for unmodified clients. This is the first place the
//! extension layer surfaces. Implemented in Phase 2 (§11.2).
