* s3: enforce authentication and JSON error format for Iceberg REST Catalog
* s3/iceberg: align error exception types with OpenAPI spec examples
* s3api: refactor AuthenticateRequest to return identity object
* s3/iceberg: propagate full identity object to request context
* s3/iceberg: differentiate NotAuthorizedException and ForbiddenException
* s3/iceberg: reject requests if authenticator is nil to prevent auth bypass
* s3/iceberg: refactor Auth middleware to build context incrementally and use switch for error mapping
* s3api: update misleading comment for authRequestWithAuthType
* s3api: return ErrAccessDenied if IAM is not configured to prevent auth bypass
* s3/iceberg: optimize context update in Auth middleware
* s3api: export CanDo for external authorization use
* s3/iceberg: enforce identity-based authorization in all API handlers
* s3api: fix compilation errors by updating internal CanDo references
* s3/iceberg: robust identity validation and consistent action usage in handlers
* s3api: complete CanDo rename across tests and policy engine integration
* s3api: fix integration tests by allowing admin access when auth is disabled and explicit gRPC ports
* duckdb
* create test bucket
