refactor(driver-twincat): extract TwinCATDriverOptions to .Contracts

Move TwinCATDriverOptions and TwinCATDataType enum to a new
Driver.TwinCAT.Contracts sibling project. TwinCATDataTypeExtensions
(which uses DriverDataType from Core.Abstractions) stays in the
runtime driver as TwinCATDataTypeExtensions.cs.

Replace two doc-comment references:
  <see cref="Core.Abstractions.PollGroupEngine"/> → <c>PollGroupEngine</c>
  <see cref="TwinCATAmsAddress.TryParse"/> → <c>TwinCATAmsAddress.TryParse</c>
per the approved decision — no compilable usings were present.

The runtime Driver.TwinCAT project gains a ProjectReference to .Contracts;
the .slnx is updated accordingly.

ZB.MOM.WW.OtOpcUa.slnx

@@ -32,6 +32,7 @@
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.csproj" />
+    <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Contracts/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Contracts.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.csproj" />
   </Folder>

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Contracts/TwinCATDataType.cs

@@ -1,5 +1,3 @@
-using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
-
 namespace ZB.MOM.WW.OtOpcUa.Driver.TwinCAT;
 
 /// <summary>
@@ -34,30 +32,3 @@ public enum TwinCATDataType
     /// <summary>UDT / FB instance. Resolved per member at discovery time.</summary>
     Structure,
 }
-
-/// <summary>Extension methods for TwinCATDataType.</summary>
-public static class TwinCATDataTypeExtensions
-{
-    /// <summary>Maps a TwinCAT data type to the equivalent driver data type.</summary>
-    /// <param name="t">The TwinCAT data type to convert.</param>
-    /// <returns>The corresponding driver data type.</returns>
-    public static DriverDataType ToDriverDataType(this TwinCATDataType t) => t switch
-    {
-        TwinCATDataType.Bool => DriverDataType.Boolean,
-        TwinCATDataType.SInt => DriverDataType.Int16,    // signed 8-bit — no narrower OPC UA atom
-        TwinCATDataType.USInt => DriverDataType.UInt16,  // unsigned 8-bit — no narrower OPC UA atom
-        TwinCATDataType.Int => DriverDataType.Int16,
-        TwinCATDataType.UInt => DriverDataType.UInt16,
-        TwinCATDataType.DInt => DriverDataType.Int32,
-        TwinCATDataType.UDInt => DriverDataType.UInt32,
-        TwinCATDataType.LInt => DriverDataType.Int64,
-        TwinCATDataType.ULInt => DriverDataType.UInt64,
-        TwinCATDataType.Real => DriverDataType.Float32,
-        TwinCATDataType.LReal => DriverDataType.Float64,
-        TwinCATDataType.String or TwinCATDataType.WString => DriverDataType.String,
-        TwinCATDataType.Time or TwinCATDataType.Date
-            or TwinCATDataType.DateTime or TwinCATDataType.TimeOfDay => DriverDataType.UInt32,
-        TwinCATDataType.Structure => DriverDataType.String,
-        _ => DriverDataType.Int32,
-    };
-}

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Contracts/TwinCATDriverOptions.cs

@@ -22,7 +22,7 @@ public sealed class TwinCATDriverOptions
     ///     rather than the driver polling. Strictly better for latency + CPU when the target
     ///     supports it (TC2 + TC3 PLC runtimes always do; some soft-PLC / third-party ADS
     ///     implementations may not). When <c>false</c>, the driver falls through to the shared
-    ///     <see cref="Core.Abstractions.PollGroupEngine"/> — same semantics as the other
+    ///     <c>PollGroupEngine</c> — same semantics as the other
     ///     libplctag-backed drivers. Set <c>false</c> for deployments where the AMS router has
     ///     notification limits you can't raise.
     /// </summary>
@@ -50,7 +50,7 @@ public sealed class TwinCATDriverOptions
 
 /// <summary>
 ///     One TwinCAT target. <paramref name="HostAddress"/> must parse via
-///     <see cref="TwinCATAmsAddress.TryParse"/>; misconfigured devices fail driver initialisation.
+///     <c>TwinCATAmsAddress.TryParse</c>; misconfigured devices fail driver initialisation.
 /// </summary>
 public sealed record TwinCATDeviceOptions(
     string HostAddress,

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Contracts/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Contracts.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+    <PropertyGroup>
+        <TargetFramework>net10.0</TargetFramework>
+        <Nullable>enable</Nullable>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    </PropertyGroup>
+    <!-- NO PackageReference. -->
+</Project>

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/TwinCATDataTypeExtensions.cs

@@ -0,0 +1,30 @@
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.TwinCAT;
+
+/// <summary>Extension methods for TwinCATDataType.</summary>
+public static class TwinCATDataTypeExtensions
+{
+    /// <summary>Maps a TwinCAT data type to the equivalent driver data type.</summary>
+    /// <param name="t">The TwinCAT data type to convert.</param>
+    /// <returns>The corresponding driver data type.</returns>
+    public static DriverDataType ToDriverDataType(this TwinCATDataType t) => t switch
+    {
+        TwinCATDataType.Bool => DriverDataType.Boolean,
+        TwinCATDataType.SInt => DriverDataType.Int16,    // signed 8-bit — no narrower OPC UA atom
+        TwinCATDataType.USInt => DriverDataType.UInt16,  // unsigned 8-bit — no narrower OPC UA atom
+        TwinCATDataType.Int => DriverDataType.Int16,
+        TwinCATDataType.UInt => DriverDataType.UInt16,
+        TwinCATDataType.DInt => DriverDataType.Int32,
+        TwinCATDataType.UDInt => DriverDataType.UInt32,
+        TwinCATDataType.LInt => DriverDataType.Int64,
+        TwinCATDataType.ULInt => DriverDataType.UInt64,
+        TwinCATDataType.Real => DriverDataType.Float32,
+        TwinCATDataType.LReal => DriverDataType.Float64,
+        TwinCATDataType.String or TwinCATDataType.WString => DriverDataType.String,
+        TwinCATDataType.Time or TwinCATDataType.Date
+            or TwinCATDataType.DateTime or TwinCATDataType.TimeOfDay => DriverDataType.UInt32,
+        TwinCATDataType.Structure => DriverDataType.String,
+        _ => DriverDataType.Int32,
+    };
+}

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.csproj

@@ -13,6 +13,7 @@
     </PropertyGroup>
 
     <ItemGroup>
+        <ProjectReference Include="..\ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Contracts\ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Contracts.csproj"/>
         <ProjectReference Include="..\..\Core\ZB.MOM.WW.OtOpcUa.Core.Abstractions\ZB.MOM.WW.OtOpcUa.Core.Abstractions.csproj"/>
         <ProjectReference Include="..\..\Core\ZB.MOM.WW.OtOpcUa.Core\ZB.MOM.WW.OtOpcUa.Core.csproj"/>
     </ItemGroup>