feat!: native-first API refactor, WASM behind feature flag

BREAKING: native functions return [u8; 32] instead of Vec<u8>.
BREAKING: WASM bindings require `wasm` feature flag.
New Blake3Error type replaces JsError for native consumers.

scripts/tpl/index.d.ts

@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
 // Copyright 2026 Thomas <[email protected]>
-//
 // @ts-nocheck
 
 export { Hasher, deriveKey, hash, hashXof, keyedHash } from './bundler/blake3_wasm_rs';