v1.18.0

[1.18.0] - 2026-06-26

Minor release: capability-scope conformance corpus. A credential grant now carries machine-checkable capability constraints, and the published vectors prove a gate enforces them without trusting the chain.

• capability_scope_v0 ships five conformance cases under tests/vectors/capability_scope_v0/: a valid grant resolves to ok, an over-limit amount and an out-of-set vendor both resolve to capability_exceeded, an argument no capability covers resolves to capability_uncovered (closed coverage: an unnamed argument is denied, not ignored), and an absent credential resolves to missing_credential. Comparisons run over Decimal with le/ge/eq/in operators, and a boolean is rejected rather than coerced.
• The independent checker reproduces every verdict and HS256 signature over RFC 8785 JCS with zero Vaara import (standard library plus the canonicalizer), so the corpus does not confirm itself. The signing payload is the grant's {alg, asserted, binding, scope, version} together with its declared capabilities.
• The cases pin two OWASP AISVS 1.0 controls, C9.2.3 (reversibility classification) and C9.2.4 (runtime enforcement by class), published 2026-06-26, as an executable reference a recipient can check independently.