HPKE

hpke-ng: Faster, Smaller, Harder HPKE for Rust

126 head-to-head benchmarks against hpke-rs and rust-hpke. hpke-ng wins 103, ties 19, loses 4. ML-KEM-1024 decap −55%, X25519 decap −41%, export −72% to −76%, end-to-end roundtrip −30% — and a type system that catches four classes of bug at compile time.