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/Models/AlarmEventArgs.cs

@@ -0,0 +1,51 @@
+namespace ZB.MOM.WW.LmxOpcUa.Client.Shared.Models;
+
+/// <summary>
+/// Event data for an alarm or condition notification from the OPC UA server.
+/// </summary>
+public sealed class AlarmEventArgs : EventArgs
+{
+    /// <summary>The name of the source object that raised the alarm.</summary>
+    public string SourceName { get; }
+
+    /// <summary>The condition type name.</summary>
+    public string ConditionName { get; }
+
+    /// <summary>The alarm severity (0-1000).</summary>
+    public ushort Severity { get; }
+
+    /// <summary>Human-readable alarm message.</summary>
+    public string Message { get; }
+
+    /// <summary>Whether the alarm should be retained in the display.</summary>
+    public bool Retain { get; }
+
+    /// <summary>Whether the alarm condition is currently active.</summary>
+    public bool ActiveState { get; }
+
+    /// <summary>Whether the alarm has been acknowledged.</summary>
+    public bool AckedState { get; }
+
+    /// <summary>The time the event occurred.</summary>
+    public DateTime Time { get; }
+
+    public AlarmEventArgs(
+        string sourceName,
+        string conditionName,
+        ushort severity,
+        string message,
+        bool retain,
+        bool activeState,
+        bool ackedState,
+        DateTime time)
+    {
+        SourceName = sourceName;
+        ConditionName = conditionName;
+        Severity = severity;
+        Message = message;
+        Retain = retain;
+        ActiveState = activeState;
+        AckedState = ackedState;
+        Time = time;
+    }
+}