IEC 61131-3 TIME/TOD now surface as TimeSpan (UA Duration); DATE/DT
surface as DateTime (UTC). The wire form stays UDINT — AdsTwinCATClient
post-processes raw values in ReadValueAsync and OnAdsNotificationEx,
and accepts native CLR types in ConvertForWrite. Added Duration to
DriverDataType (back-compat: existing switches default to BaseDataType
for unknown enum values) and mapped it to DataTypeIds.Duration in
DriverNodeManager.
Closes#306
