Migrate historian from SQL to aahClientManaged SDK and resolve all OPC UA Part 11 gaps

Replace direct SQL queries against Historian Runtime database with the Wonderware
Historian managed SDK (ArchestrA.HistorianAccess). Add HistoryServerCapabilities node,
AggregateFunctions folder, continuation points, ReadAtTime interpolation, ReturnBounds,
ReadModified rejection, HistoricalDataConfiguration per node, historical event access,
and client-side StandardDeviation aggregate support. Remove screenshot tests.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/ZB.MOM.WW.LmxOpcUa.Host/Historian/HistoryContinuationPoint.cs

@@ -0,0 +1,88 @@
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using Opc.Ua;
+using Serilog;
+
+namespace ZB.MOM.WW.LmxOpcUa.Host.Historian
+{
+    /// <summary>
+    ///     Manages continuation points for OPC UA HistoryRead requests that return
+    ///     more data than the per-request limit allows.
+    /// </summary>
+    internal sealed class HistoryContinuationPointManager
+    {
+        private static readonly ILogger Log = Serilog.Log.ForContext<HistoryContinuationPointManager>();
+
+        private readonly ConcurrentDictionary<Guid, StoredContinuation> _store = new();
+        private readonly TimeSpan _timeout = TimeSpan.FromMinutes(5);
+
+        /// <summary>
+        ///     Stores remaining data values and returns a continuation point identifier.
+        /// </summary>
+        public byte[] Store(List<DataValue> remaining)
+        {
+            PurgeExpired();
+            var id = Guid.NewGuid();
+            _store[id] = new StoredContinuation(remaining, DateTime.UtcNow);
+            Log.Debug("Stored history continuation point {Id} with {Count} remaining values", id, remaining.Count);
+            return id.ToByteArray();
+        }
+
+        /// <summary>
+        ///     Retrieves and removes the remaining data values for a continuation point.
+        ///     Returns null if the continuation point is invalid or expired.
+        /// </summary>
+        public List<DataValue>? Retrieve(byte[] continuationPoint)
+        {
+            if (continuationPoint == null || continuationPoint.Length != 16)
+                return null;
+
+            var id = new Guid(continuationPoint);
+            if (!_store.TryRemove(id, out var stored))
+                return null;
+
+            if (DateTime.UtcNow - stored.CreatedAt > _timeout)
+            {
+                Log.Debug("History continuation point {Id} expired", id);
+                return null;
+            }
+
+            return stored.Values;
+        }
+
+        /// <summary>
+        ///     Releases a continuation point without retrieving its data.
+        /// </summary>
+        public void Release(byte[] continuationPoint)
+        {
+            if (continuationPoint == null || continuationPoint.Length != 16)
+                return;
+
+            var id = new Guid(continuationPoint);
+            _store.TryRemove(id, out _);
+        }
+
+        private void PurgeExpired()
+        {
+            var cutoff = DateTime.UtcNow - _timeout;
+            foreach (var kvp in _store)
+            {
+                if (kvp.Value.CreatedAt < cutoff)
+                    _store.TryRemove(kvp.Key, out _);
+            }
+        }
+
+        private sealed class StoredContinuation
+        {
+            public StoredContinuation(List<DataValue> values, DateTime createdAt)
+            {
+                Values = values;
+                CreatedAt = createdAt;
+            }
+
+            public List<DataValue> Values { get; }
+            public DateTime CreatedAt { get; }
+        }
+    }
+}