refactor(logging): adopt ZB.MOM.WW.Telemetry.Serilog bootstrap

Swap the gateway process logging from the default Microsoft.Extensions.Logging
provider onto the shared ZB.MOM.WW.Telemetry.Serilog two-stage bootstrap.

- Add a cross-repo ProjectReference to ZB.MOM.WW.Telemetry.Serilog (transitively
  brings the Telemetry core package); the referenced project resolves its own
  Directory.Build.props / Directory.Packages.props so it does not perturb this build.
- Replace MEL wiring in GatewayApplication with builder.AddZbSerilog(ServiceName=
  "mxgateway"; SiteId/NodeRole read from MxGateway:Telemetry when present) and add
  app.UseSerilogRequestLogging().
- Add a Serilog section (Console + daily rolling File sinks, MinimumLevel) to
  appsettings.json and a MinimumLevel override to appsettings.Development.json,
  replacing the old MEL Logging sections.

The net48/x86 worker is untouched. Correlation scope + redaction move to the
shared ILogRedactor seam in the follow-up commit.

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

@@ -15,6 +15,13 @@
 
   <ItemGroup>
     <ProjectReference Include="..\ZB.MOM.WW.MxGateway.Contracts\ZB.MOM.WW.MxGateway.Contracts.csproj" />
+    <!--
+      Shared structured-logging bootstrap (ZB.MOM.WW.Telemetry.Serilog) lives in the sibling
+      scadaproj workspace. Cross-repo ProjectReference: the referenced project resolves its own
+      Directory.Build.props / Directory.Packages.props from its own tree, so it does not perturb
+      this repo's build settings. It transitively brings the ZB.MOM.WW.Telemetry core package.
+    -->
+    <ProjectReference Include="..\..\..\scadaproj\ZB.MOM.WW.Telemetry\src\ZB.MOM.WW.Telemetry.Serilog\ZB.MOM.WW.Telemetry.Serilog.csproj" />
   </ItemGroup>
 
 </Project>