[Defect]: Duplicate BLAKE2b-HMAC variant in Cryptography Registry

[Mehrn0ush]

Describe the defect

Where:
schema/cryptography-defs.json

What:
The BLAKE2 family variants include a duplicate entry for:

• BLAKE2b-(160|256|384|512)-HMAC (primitive: mac)

Impact:
Duplicate variant patterns can cause ambiguity and inconsistent processing across consumers.

Additional context

Data-quality cleanup only. No new algorithms or schema behavior changes.

[stevespringett]

cc: @bhess