Add cross-platform OPC UA client stack: shared library, CLI tool, and Avalonia UI

Implements Client.Shared (IOpcUaClientService with connection lifecycle, failover,
browse, read/write, subscriptions, alarms, history, redundancy), Client.CLI (8 CliFx
commands mirroring tools/opcuacli-dotnet), and Client.UI (Avalonia desktop app with
tree browser, read/write, subscriptions, alarms, and history tabs). All three target
.NET 10 and are covered by 249 unit tests.

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

src/ZB.MOM.WW.LmxOpcUa.Client.Shared/Adapters/ISubscriptionAdapter.cs

@@ -0,0 +1,47 @@
+using Opc.Ua;
+
+namespace ZB.MOM.WW.LmxOpcUa.Client.Shared.Adapters;
+
+/// <summary>
+/// Abstracts OPC UA subscription and monitored item management.
+/// </summary>
+internal interface ISubscriptionAdapter : IDisposable
+{
+    uint SubscriptionId { get; }
+
+    /// <summary>
+    /// Adds a data-change monitored item and returns its client handle for tracking.
+    /// </summary>
+    /// <param name="nodeId">The node to monitor.</param>
+    /// <param name="samplingIntervalMs">The sampling interval in milliseconds.</param>
+    /// <param name="onDataChange">Callback when data changes. Receives (nodeIdString, DataValue).</param>
+    /// <param name="ct">Cancellation token.</param>
+    /// <returns>A client handle that can be used to remove the item.</returns>
+    Task<uint> AddDataChangeMonitoredItemAsync(NodeId nodeId, int samplingIntervalMs, Action<string, DataValue> onDataChange, CancellationToken ct = default);
+
+    /// <summary>
+    /// Removes a previously added monitored item by its client handle.
+    /// </summary>
+    Task RemoveMonitoredItemAsync(uint clientHandle, CancellationToken ct = default);
+
+    /// <summary>
+    /// Adds an event monitored item with the given event filter.
+    /// </summary>
+    /// <param name="nodeId">The node to monitor for events.</param>
+    /// <param name="samplingIntervalMs">The sampling interval.</param>
+    /// <param name="filter">The event filter defining which fields to select.</param>
+    /// <param name="onEvent">Callback when events arrive. Receives the event field list.</param>
+    /// <param name="ct">Cancellation token.</param>
+    /// <returns>A client handle for the monitored item.</returns>
+    Task<uint> AddEventMonitoredItemAsync(NodeId nodeId, int samplingIntervalMs, EventFilter filter, Action<EventFieldList> onEvent, CancellationToken ct = default);
+
+    /// <summary>
+    /// Requests a condition refresh for this subscription.
+    /// </summary>
+    Task ConditionRefreshAsync(CancellationToken ct = default);
+
+    /// <summary>
+    /// Removes all monitored items and deletes the subscription.
+    /// </summary>
+    Task DeleteAsync(CancellationToken ct = default);
+}