// Unlicense — cochranblock.org
// Contributors: Mattbusel (XFactor), GotEmCoach, KOVA, Claude Opus 4.6, SuperNinja, Composer 1.5, Google Gemini Pro 3
use Hkdf;
use Sha256;
use cratet18;
/// f31 = key_derive — HKDF, context-specific. Why: Kova forbids unwrap in lib; expand can fail.
/// f32 = key_derive_default — HKDF, default context. Why: session signing key derivation.