Implement LmxOpcUa server — all 6 phases complete

Full OPC UA server on .NET Framework 4.8 (x86) exposing AVEVA System
Platform Galaxy tags via MXAccess. Mirrors Galaxy object hierarchy as
OPC UA address space, translating contained-name browse paths to
tag-name runtime references.

Components implemented:
- Configuration: AppConfiguration with 4 sections, validator
- Domain: ConnectionState, Quality, Vtq, MxDataTypeMapper, error codes
- MxAccess: StaComThread, MxAccessClient (partial classes), MxProxyAdapter
  using strongly-typed ArchestrA.MxAccess COM interop
- Galaxy Repository: SQL queries (hierarchy, attributes, change detection),
  ChangeDetectionService with auto-rebuild on deploy
- OPC UA Server: LmxNodeManager (CustomNodeManager2), LmxOpcUaServer,
  OpcUaServerHost with programmatic config, SecurityPolicy None
- Status Dashboard: HTTP server with HTML/JSON/health endpoints
- Integration: Full 14-step startup, graceful shutdown, component wiring

175 tests (174 unit + 1 integration), all passing.

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

tests/ZB.MOM.WW.LmxOpcUa.Tests/MxAccess/MxAccessClientMonitorTests.cs

@@ -0,0 +1,72 @@
+using System;
+using System.Threading.Tasks;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.LmxOpcUa.Host.Configuration;
+using ZB.MOM.WW.LmxOpcUa.Host.Domain;
+using ZB.MOM.WW.LmxOpcUa.Host.Metrics;
+using ZB.MOM.WW.LmxOpcUa.Host.MxAccess;
+using ZB.MOM.WW.LmxOpcUa.Tests.Helpers;
+
+namespace ZB.MOM.WW.LmxOpcUa.Tests.MxAccess
+{
+    public class MxAccessClientMonitorTests : IDisposable
+    {
+        private readonly StaComThread _staThread;
+        private readonly FakeMxProxy _proxy;
+        private readonly PerformanceMetrics _metrics;
+
+        public MxAccessClientMonitorTests()
+        {
+            _staThread = new StaComThread();
+            _staThread.Start();
+            _proxy = new FakeMxProxy();
+            _metrics = new PerformanceMetrics();
+        }
+
+        public void Dispose()
+        {
+            _staThread.Dispose();
+            _metrics.Dispose();
+        }
+
+        [Fact]
+        public async Task Monitor_ReconnectsOnDisconnect()
+        {
+            var config = new MxAccessConfiguration
+            {
+                MonitorIntervalSeconds = 1,
+                AutoReconnect = true
+            };
+            var client = new MxAccessClient(_staThread, _proxy, config, _metrics);
+
+            await client.ConnectAsync();
+            await client.DisconnectAsync();
+
+            client.StartMonitor();
+
+            // Wait for monitor to detect disconnect and reconnect
+            await Task.Delay(2500);
+
+            client.StopMonitor();
+            client.State.ShouldBe(ConnectionState.Connected);
+            client.ReconnectCount.ShouldBeGreaterThan(0);
+            client.Dispose();
+        }
+
+        [Fact]
+        public async Task Monitor_StopsOnCancel()
+        {
+            var config = new MxAccessConfiguration { MonitorIntervalSeconds = 1 };
+            var client = new MxAccessClient(_staThread, _proxy, config, _metrics);
+
+            await client.ConnectAsync();
+            client.StartMonitor();
+            client.StopMonitor();
+
+            // Should not throw
+            await Task.Delay(200);
+            client.Dispose();
+        }
+    }
+}