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>

tests/ZB.MOM.WW.LmxOpcUa.Client.CLI.Tests/TestConsoleHelper.cs

@@ -0,0 +1,35 @@
+using CliFx.Infrastructure;
+
+namespace ZB.MOM.WW.LmxOpcUa.Client.CLI.Tests;
+
+/// <summary>
+/// Helper for creating CliFx <see cref="FakeInMemoryConsole"/> instances and reading their output.
+/// </summary>
+public static class TestConsoleHelper
+{
+    /// <summary>
+    /// Creates a new <see cref="FakeInMemoryConsole"/> for testing.
+    /// </summary>
+    public static FakeInMemoryConsole CreateConsole()
+    {
+        return new FakeInMemoryConsole();
+    }
+
+    /// <summary>
+    /// Reads all text written to the console's standard output.
+    /// </summary>
+    public static string GetOutput(FakeInMemoryConsole console)
+    {
+        console.Output.Flush();
+        return console.ReadOutputString();
+    }
+
+    /// <summary>
+    /// Reads all text written to the console's standard error.
+    /// </summary>
+    public static string GetError(FakeInMemoryConsole console)
+    {
+        console.Error.Flush();
+        return console.ReadErrorString();
+    }
+}