Audit finding H-20: no audit trail of model I/O for seahaven-alex,
which returns payments, invoices, WO/PO, and HR/SA8000 data.
S3 bucket (Glacier at 90d, expire 365d) + CloudWatch log group (90d)
+ delivery role assumable only by bedrock.amazonaws.com scoped by
SourceAccount/SourceArn. The account-level logging configuration has
no CloudFormation resource type, so it is applied via CLI post-deploy
(documented in the construct header) - same pattern as the Config
recorder (INFRA-17).
Cross-reviewed: no BLOCKs. Verified live: converse invocation logged
to /aws/bedrock/model-invocations.
