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/Domain/MxErrorCodesTests.cs

@@ -0,0 +1,46 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.LmxOpcUa.Host.Domain;
+
+namespace ZB.MOM.WW.LmxOpcUa.Tests.Domain
+{
+    public class MxErrorCodesTests
+    {
+        [Theory]
+        [InlineData(1008, "Invalid reference")]
+        [InlineData(1012, "Wrong data type")]
+        [InlineData(1013, "Not writable")]
+        [InlineData(1014, "Request timed out")]
+        [InlineData(1015, "Communication failure")]
+        [InlineData(1016, "Not connected")]
+        public void GetMessage_KnownCodes_ContainsDescription(int code, string expectedSubstring)
+        {
+            MxErrorCodes.GetMessage(code).ShouldContain(expectedSubstring);
+        }
+
+        [Fact]
+        public void GetMessage_UnknownCode_ReturnsUnknown()
+        {
+            MxErrorCodes.GetMessage(9999).ShouldContain("Unknown");
+            MxErrorCodes.GetMessage(9999).ShouldContain("9999");
+        }
+
+        [Theory]
+        [InlineData(1008, Quality.BadConfigError)]
+        [InlineData(1012, Quality.BadConfigError)]
+        [InlineData(1013, Quality.BadOutOfService)]
+        [InlineData(1014, Quality.BadCommFailure)]
+        [InlineData(1015, Quality.BadCommFailure)]
+        [InlineData(1016, Quality.BadNotConnected)]
+        public void MapToQuality_KnownCodes(int code, Quality expected)
+        {
+            MxErrorCodes.MapToQuality(code).ShouldBe(expected);
+        }
+
+        [Fact]
+        public void MapToQuality_UnknownCode_ReturnsBad()
+        {
+            MxErrorCodes.MapToQuality(9999).ShouldBe(Quality.Bad);
+        }
+    }
+}