refactor(driver-focas): extract FocasDriverOptions to .Contracts

Move FocasDriverOptions (and companion option types), FocasCncSeries,
and the FocasDataType enum to a new Driver.FOCAS.Contracts sibling
project. FocasDataTypeExtensions (which uses DriverDataType from
Core.Abstractions) stays in the runtime driver as FocasDataTypeExtensions.cs.

Convert two doc-comment references:
  <see cref="FocasDriver.InitializeAsync"/> → <c>FocasDriver.InitializeAsync</c>
  <see cref="FocasAddress.TryParse"/> → <c>FocasAddress.TryParse</c>
per the approved decision — no compilable usings were present in the
moved files.

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

ZB.MOM.WW.OtOpcUa.slnx

@@ -35,6 +35,7 @@
     <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.FOCAS.Contracts/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Contracts.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.csproj" />
   </Folder>
   <Folder Name="/src/Drivers/Driver CLIs/">

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Contracts/FocasDataType.cs

@@ -1,5 +1,3 @@
-using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
-
 namespace ZB.MOM.WW.OtOpcUa.Driver.FOCAS;
 
 /// <summary>
@@ -24,19 +22,3 @@ public enum FocasDataType
     /// <summary>ASCII string (alarm text, parameter names, some PMC string areas).</summary>
     String,
 }
-
-public static class FocasDataTypeExtensions
-{
-    /// <summary>Converts a FOCAS data type to the corresponding driver data type.</summary>
-    /// <param name="t">The FOCAS data type to convert.</param>
-    /// <returns>The equivalent driver data type.</returns>
-    public static DriverDataType ToDriverDataType(this FocasDataType t) => t switch
-    {
-        FocasDataType.Bit => DriverDataType.Boolean,
-        FocasDataType.Byte or FocasDataType.Int16 or FocasDataType.Int32 => DriverDataType.Int32,
-        FocasDataType.Float32 => DriverDataType.Float32,
-        FocasDataType.Float64 => DriverDataType.Float64,
-        FocasDataType.String => DriverDataType.String,
-        _ => DriverDataType.Int32,
-    };
-}

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Contracts/FocasDriverOptions.cs

@@ -96,7 +96,7 @@ public sealed class FocasAlarmProjectionOptions
 
 /// <summary>
 ///     One CNC the driver talks to. <paramref name="Series"/> enables per-series
-///     address validation at <see cref="FocasDriver.InitializeAsync"/>; leave as
+///     address validation at <c>FocasDriver.InitializeAsync</c>; leave as
 ///     <see cref="FocasCncSeries.Unknown"/> to skip validation (legacy behaviour).
 /// </summary>
 public sealed record FocasDeviceOptions(
@@ -106,7 +106,7 @@ public sealed record FocasDeviceOptions(
 
 /// <summary>
 ///     One FOCAS-backed OPC UA variable. <paramref name="Address"/> is the canonical FOCAS
-///     address string that parses via <see cref="FocasAddress.TryParse"/> —
+///     address string that parses via <c>FocasAddress.TryParse</c> —
 ///     <c>X0.0</c> / <c>R100</c> / <c>PARAM:1815/0</c> / <c>MACRO:500</c>.
 /// </summary>
 public sealed record FocasTagDefinition(

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Contracts/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.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. NO ProjectReference. -->
+</Project>

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/FocasDataTypeExtensions.cs

@@ -0,0 +1,19 @@
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.FOCAS;
+
+public static class FocasDataTypeExtensions
+{
+    /// <summary>Converts a FOCAS data type to the corresponding driver data type.</summary>
+    /// <param name="t">The FOCAS data type to convert.</param>
+    /// <returns>The equivalent driver data type.</returns>
+    public static DriverDataType ToDriverDataType(this FocasDataType t) => t switch
+    {
+        FocasDataType.Bit => DriverDataType.Boolean,
+        FocasDataType.Byte or FocasDataType.Int16 or FocasDataType.Int32 => DriverDataType.Int32,
+        FocasDataType.Float32 => DriverDataType.Float32,
+        FocasDataType.Float64 => DriverDataType.Float64,
+        FocasDataType.String => DriverDataType.String,
+        _ => DriverDataType.Int32,
+    };
+}

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

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