CredentialIssuer API

issuer = CredentialIssuer(signer=signer, keypair=keypair)

# Issue single credential
cred = issuer.issue(
    issuer_did, subject_did,
    credential_types=["AgentCapability"],
    claims={"capability": "tool:search"},
    expiration_seconds=86400,
)

# Batch issue
creds = issuer.batch_issue([...credential_specs])