feat(p9): Capability Broker — governed egress + fail-closed gate + obligations

Tasks 9.1+9.2: contracts (CapabilityRequest/Result/Provider, PolicyObligation) +
service CapabilityBroker that fails closed via opa (PolicyDeniedError, nothing sent),
enforces obligations before any provider call (DENY_OUTBOUND/REVIEW → BLOCKED;
MASK/REDACT → mask payload field), then routes to a CapabilityProviderRegistry
(SandboxProvider default; env-gated HttpProvider overrides per channel; unknown
channel fails closed). 5 tests: allow/deny/block/redact/unknown-channel.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/iios-contracts/src/index.ts

@@ -3,6 +3,7 @@ export * from './enums';
 export * from './ingest';
 export * from './ports';
 export * from './inference';
+export * from './capability';
 export * from './events';
 export * from './commands';
 export * from './errors';