[FEATURE]: Add AES-GCM-SIV AEAD variant in Cryptography Registry

[Mehrn0ush]

Describe the defect

Where:
schema/cryptography-defs.json

What:
The AES algorithm family includes AEAD variants (e.g., GCM, CCM), but the registry is missing the standardized misuse-resistant AEAD mode AES-GCM-SIV (RFC 8452).

Impact:
Registry consumers cannot consistently identify or normalize AES-GCM-SIV usage across CBOM/SBOM pipelines, which affects reporting and policy enforcement.

Additional context

Registry-only completeness fix: add AES-GCM-SIV as an ae variant under the existing AES family. No schema or specification behavior changes.

[stevespringett]

cc: @bhess

[jkowalleck]

not a defect, but a missing feature.