fix: route all Docker builds through local Nexus mirrors

- All Node Dockerfiles rewritten with NODE_IMAGE + NPM_REGISTRY build args
  defaulting to local Nexus proxies (171.22.25.73:5000/library/node:20-alpine
  and http://mirror:8081/repository/npm-group/)
- Add extra_hosts: mirror:host-gateway to every build section so the
  mirror hostname resolves during docker build
- Replace nuget.org with nuget.docker.config (Nexus mirror) in api/admin-api
  Dockerfiles to fix NuGet restore in Iranian network
- Rewrite admin-web and website Dockerfiles (were referencing non-existent
  meezi-node:20-alpine base image with no npm install step)
- Update dotnet image defaults to 171.22.25.73:5002 MCR proxy in admin-api
  and docker-compose.admin.yml

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

docker-compose.admin.yml

@@ -13,9 +13,11 @@ services:
     build:
       context: .
       dockerfile: docker/admin-api/Dockerfile
+      extra_hosts:
+        - "mirror:host-gateway"
       args:
-        DOTNET_SDK_IMAGE: ${DOTNET_SDK_IMAGE:-mcr.microsoft.com/dotnet/sdk:10.0}
-        DOTNET_ASPNET_IMAGE: ${DOTNET_ASPNET_IMAGE:-mcr.microsoft.com/dotnet/aspnet:10.0}
+        DOTNET_SDK_IMAGE: ${DOTNET_SDK_IMAGE:-171.22.25.73:5002/dotnet/sdk:10.0}
+        DOTNET_ASPNET_IMAGE: ${DOTNET_ASPNET_IMAGE:-171.22.25.73:5002/dotnet/aspnet:10.0}
     container_name: meezi-admin-api
     restart: unless-stopped
     depends_on:
@@ -46,7 +48,11 @@ services:
     build:
       context: .
       dockerfile: docker/admin-web/Dockerfile
+      extra_hosts:
+        - "mirror:host-gateway"
       args:
+        NODE_IMAGE: ${NODE_IMAGE:-171.22.25.73:5000/library/node:20-alpine}
+        NPM_REGISTRY: ${NPM_REGISTRY:-http://mirror:8081/repository/npm-group/}
         NEXT_PUBLIC_ADMIN_API_URL: ${NEXT_PUBLIC_ADMIN_API_URL:-http://localhost:5081}
     container_name: meezi-admin-web
     restart: unless-stopped