Final review M3: SecretReferenceScanner.TryParseSecretReference (trimmed, case-insensitive
prefix, trimmed name, empty = not a reference, ${secret:} never matches) is used by the scanner
and by MxGatewayDataConnection's ApiKey resolution, so a padded or case-variant reference
resolves the name central ships. A bare 'secret:' ApiKey now fails closed. M7: unit test pins
stamped hash == ComputeCurrentArtifactHashesAsync with a non-empty Secrets list.
Joseph Doherty