Route all package mirrors through local Nexus

Point Docker, NuGet, and npm pulls at the Nexus group repos on
171.22.25.73:8081 for both CI/CD and local builds, so the pipeline and
developers no longer depend on Docker Hub, MCR, nuget.org, or npmjs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

nuget.docker.config

@@ -1,10 +1,12 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- NuGet config for Docker builds — routes restores through Liara NuGet mirror. -->
+<!-- NuGet config for Docker builds — routes restores through local Nexus mirror. -->
 <configuration>
   <packageSources>
     <clear />
-    <add key="liara-nuget" value="https://package-mirror.liara.ir/repository/nuget/index.json"
-         protocolVersion="3" />
+    <add key="nexus"
+         value="http://171.22.25.73:8081/repository/nuget-group/index.json"
+         protocolVersion="3"
+         allowInsecureConnections="true" />
   </packageSources>
   <config>
     <add key="http_retry_count" value="8" />