v1.1.0

[1.1.0] - 2026-06-18

Minor release: the credential broker, Vaara's authority layer. Observability gains an
enforcement edge. The proxy can mint a signed, short-lived credential bound to a specific
attestation digest (transitively the mediation receipt) and scoped to one tool plus an
args commitment plus tenant. A gateway in front of a protected tool refuses any call that
lacks a valid, unexpired, non-revoked, attestation-bound grant. Bypass stops being silent
and successful; it becomes "defeat the broker first." This is detection, not a
mathematical completeness claim.

• New vaara.credential package: grant types, parse, emit, verify, and the
  CredentialGateway. The grant reuses the SEP-2787 signing stack (HS256 / ES256 / RS256
  over RFC 8785 JCS), so the grant key matches the attestation and receipt key.
• Proxy minting is gated behind _mint_credentials, default off. No runtime behavior
  changes for existing deployments until an operator turns it on with an attestation key
  configured.
• Conformance vectors under conformance/sep2828/credential_grant_v0/ with a checker that
  verifies grants without importing Vaara, so an independent implementer can recompute the
  format. Five verdict vectors covering valid, expired, wrong-scope, revoked, and tampered
  grants.
• Design spec at docs/design/credential-broker-spec.md covering the grant schema, the
  binding chain to the receipt, the threat model, and the honest limits of the approach.