refactor(driver-galaxy): extract GalaxyDriverOptions to .Contracts

Move GalaxyDriverOptions (and nested records GalaxyGatewayOptions,
GalaxyMxAccessOptions, GalaxyRepositoryOptions, GalaxyReconnectOptions)
from Config/GalaxyDriverOptions.cs into a new Driver.Galaxy.Contracts
sibling project at the contracts root (no Config/ subdirectory). The
existing namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Config is preserved
unchanged — it is a runtime ABI concern and all consumers already import
it via the namespace qualifier.

No doc-comment substitutions required — the only cref in the file
(<see cref="ApiKeySecretRef"/>) is an intra-type parameter reference
that resolves within the contracts project itself.

The options file had no using directives and no NuGet type surface;
the contracts project is dependency-free. The runtime Driver.Galaxy
project gains a ProjectReference to .Contracts; the .slnx is updated
accordingly.

ZB.MOM.WW.OtOpcUa.slnx

@@ -21,6 +21,7 @@
   </Folder>
   <Folder Name="/src/Drivers/">
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.csproj" />
+    <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Contracts/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Contracts.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Client/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Client.csproj" />
     <Project Path="src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Modbus/ZB.MOM.WW.OtOpcUa.Driver.Modbus.csproj" />

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

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