feat(opcuaclient): subscription tuning, OperationLimits chunking, diagnostics counters, revocation options, DiscoveryUrl (#273 #275 #276 #277 #278)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

docs/Historian.md

@@ -431,6 +431,17 @@ RetrievalMode.Integral`) — no client-side scaling. (This replaces the retired
 likewise a native gateway mode. Bucket status codes and timestamps are preserved unchanged; empty / null
 buckets surface as `BadNoData`.
 
+### Aggregate set and `BadAggregateNotSupported` (#285)
+
+`HistoryAggregateType` carries the wider Part 13 set (Interpolative, TimeAverage, Start, End, Delta, Range,
+Min/MaxActualTime, Start/EndBound, DeltaBounds, DurationGood/Bad, PercentGood/Bad, WorstQuality,
+NumberOfTransitions, AnnotationCount, StandardDeviationPopulation, VariancePopulation); `OtOpcUaNodeManager.MapAggregate`
+maps each standard aggregate NodeId. The **HistorianGateway** backend only has retrieval modes for the original
+five (Average, Minimum, Maximum, Total, Count): for any other member `AggregateModeMapper` throws
+`HistoryAggregateNotSupportedException`, which the HistoryRead path turns into `BadAggregateNotSupported` for that
+node only (not a generic failure, and not counted as a backend fault). The OPC UA Client driver forwards every
+member upstream. A NodeId outside the mapped set (e.g. `StandardDeviationSample`) is still `BadAggregateNotSupported`.
+
 ### Known limitations
 
 - **Processed and AtTime are single-shot** (no continuation points). Unlike Raw, neither