chore: Update production workflow to use Nexus registry (no proxy needed)

- Changed Dockerfile base images to use 194.5.195.53:32082 (Nexus)
- Updated workflow to use docker-sshpass image from Nexus
- Removed HTTP_PROXY/HTTPS_PROXY dependencies
- Changed deploy method to SSH instead of kubeconfig
- Registry: 194.5.195.53:30080 (Gitea internal)
- K8S Server: 45.149.79.127 (Production)

src/BackOffice.BFF.WebApi/Dockerfile

@@ -1,10 +1,10 @@
-FROM mcr.microsoft.com/dotnet/aspnet:9.0 AS base
+FROM 194.5.195.53:32082/dotnet/aspnet:9.0 AS base
 USER $APP_UID
 WORKDIR /app
 EXPOSE 8080
 EXPOSE 8081
 
-FROM mcr.microsoft.com/dotnet/sdk:9.0 AS build
+FROM 194.5.195.53:32082/dotnet/sdk:9.0 AS build
 ARG BUILD_CONFIGURATION=Release
 WORKDIR /src
 COPY ["BackOffice.BFF.WebApi/NuGet.config", "NuGet.config"]