feat(core-audit): wrap bound auditLog with TraceIdEnrichingAuditLog

bindAudit now wraps the inner sink/fan-out with TraceIdEnrichingAuditLog so
all sinks receive AuditEntry.correlationId auto-populated from the active
OTel span. bind-audit.test.ts assertions updated to check instanceof
TraceIdEnrichingAuditLog first, then .inner for the concrete sink type.
TraceIdEnrichingAuditLog exported from the package barrel.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/core-audit/src/index.ts

@@ -6,6 +6,7 @@ export { PayloadAuditLog } from "./payload-audit-log";
 export { MultiSinkAuditLog } from "./multi-sink-audit-log";
 export { auditLogsCollection } from "./audit-logs-collection";
 export { bindAudit, type BindAuditOpts } from "./di/bind-audit";
+export { TraceIdEnrichingAuditLog } from "./trace-id-enriching-audit-log";
 export { AUDIT_SYMBOLS } from "./di/symbols";
 // Phase 3 — GDPR erasure
 export { pseudonymize } from "./pseudonymize";