POST /api/issuer/:did/credentials/:credential_id/revoke

POST /api/issuer/did:alyra:issuer.../credentials/aly:uuid/revoke HTTP/1.1
Authorization: Bearer <jwt>

{
  "success": true,
  "message": "Credential revoked successfully",
  "credential": {
    "id": "aly:uuid",
    "issuer_did": "did:alyra:issuer...",
    "owner_did": "did:alyra:holder...",
    "status": "revoked",
    "revocation_blockchain_tx": "0x..."
  }
}