Driver.Historian.Gateway-003 (Medium): both were exercised only by the
env-gated Category=LiveIntegration suite (skips cleanly offline) or only
indirectly through FasterLogHistorizationOutboxTests with single-char
ASCII tags. Adds direct offline unit coverage for the value writer's
ack-to-bool mapping, timestamp presence/absence, and non-throwing
contract (via the existing FakeHistorianGatewayClient double), and for
the serializer's Serialize/Deserialize round trip incl. a multi-byte
UTF-8 tag, an empty tag, and ushort/double boundaries.
Joseph Doherty
a86a09767c