Rust crypto core: FrodoKEM port, hybrid suite, Fury, STREAM, key files

FrodoKEM-640-SHAKE is ported from CIRCL v1.6.4 (the RustCrypto crate
implements the incompatible ISO variant) and reproduces the reference
NIST KAT digest. ML-KEM-768 comes from RustCrypto ml-kem. Derivation,
encapsulation, implicit rejection, KEK, header MAC, header parsing,
STREAM and Argon2id key files all match vectors from the Go oracle, Go's
files decrypt in Rust, and Go decrypts Rust's.

Co-Authored-By: Claude <noreply@anthropic.com>

src/lib.rs

@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+//! vault: a post-quantum encrypted file vault. The binary is a thin wrapper
+//! around [`cli::main`]; the library exists so integration tests and
+//! benchmarks can reach the same code.
+
+#![deny(unsafe_op_in_unsafe_fn)]
+
+pub mod crypto;
+pub mod keyfile;
+pub mod platform;
+pub mod rng;
+pub mod secret;
+pub mod util;