build: copy Server appsettings.json to publish output

Microsoft.NET.Sdk doesn't auto-include appsettings.json the way Web SDK
does, so dotnet publish was leaving it behind. Without it next to the
EXE the Windows-service-mode host can't find Node + ConfigDb config and
the install scripts had to copy it by hand.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ZB.MOM.WW.OtOpcUa.Server/ZB.MOM.WW.OtOpcUa.Server.csproj

@@ -51,6 +51,10 @@
         <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Server.Tests"/>
     </ItemGroup>
 
+    <ItemGroup>
+        <None Update="appsettings.json" CopyToOutputDirectory="PreserveNewest"/>
+    </ItemGroup>
+
     <ItemGroup>
         <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-37gx-xxp4-5rgx"/>
         <NuGetAuditSuppress Include="https://github.com/advisories/GHSA-w3x6-4m5h-cxqf"/>