feat: replace deprecated ExpandedKeyEncoding with seed serialization, derive ZeroizeOnDrop

- Add ZeroizeOnDrop bound to Hash trait
- Replace manual Drop impls on Ke2Builder and KemKe2Builder with derive_where
- Migrate KEM decapsulation key serialization from expanded form to 64-byte seed (KeyInit/KeyExport)
- Fix voprf deserialization to pass exact-length slices
- Bump voprf-vx to 1.0.0-rc.1
- Regenerate test vectors

src/tests/full_test.rs

@@ -738,14 +738,10 @@ fn generate_test_vectors() -> Result<(), ProtocolError> {
     #[rustfmt::skip]
     output.push_str(
         "\
+        // SPDX-License-Identifier: MIT OR Apache-2.0\n\
+        // Copyright (c) VexaHub and contributors.\n\
         // Copyright (c) Meta Platforms, Inc. and affiliates.\n\
         //\n\
-        // This source code is dual-licensed under either the MIT license found in the\n\
-        // LICENSE-MIT file in the root directory of this source tree or the Apache\n\
-        // License, Version 2.0 found in the LICENSE-APACHE file in the root directory\n\
-        // of this source tree. You may select, at your option, one of the above-listed\n\
-        // licenses.\n\
-        //\n\
         // To regenerate these test vectors, run:\n\
         // FULL_TEST_VECTORS_FILE=src/tests/full_test_vectors.rs cargo test --features curve25519,ecdsa,ed25519 -- generate_test_vectors\n\
         \n\