extract docinfo library

CLAUDE.md

@@ -43,7 +43,7 @@ fuz_util is a **foundational utility library**:
 - `iterator.ts` - iterator helpers
 - `bytes.ts` - binary data conversion (`to_bytes`)
 - `hex.ts` - hex encoding (`to_hex`)
-- `hash_blake3.ts` - BLAKE3 hashing (`hash_blake3`, sync, 64-char hex, via
+- `hash_blake3.ts` - BLAKE3 hashing (`hash_blake3`, sync, 64-char hex; `Blake3Hash` Zod schema, via
   `@fuzdev/blake3_wasm`)
 - `hash.ts` - `hash_sha256` (Web Crypto SHA-256, async), `hash_insecure` (DJB2
   for non-security uses)