feat: change deriveChildKey to hkdf sha256 and create deriveBlakeChildKey that hashes based on the initial blake3 route used by s5

src/keys.ts

@@ -1,9 +1,18 @@
 import { blake3 } from "@noble/hashes/blake3";
 import { concatBytes } from "@noble/hashes/utils";
+import { hkdf } from "@noble/hashes/hkdf";
+import { sha256 } from "@noble/hashes/sha256";
 
 export function deriveChildKey(
   parentKey: Uint8Array,
   tweak: string,
+): Uint8Array {
+  return hkdf(sha256, parentKey, undefined, tweak, 32);
+}
+
+export function deriveBlakeChildKey(
+  parentKey: Uint8Array,
+  tweak: string,
 ): Uint8Array {
   const tweakHash = blake3(tweak);