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/Dockerfile

@@ -1,4 +1,4 @@
-FROM mcr.microsoft.com/dotnet/sdk:9.0 AS build
+FROM 194.5.195.53:32082/dotnet/sdk:9.0 AS build
 WORKDIR /src
 
 # Copy NuGet config and project file
@@ -16,7 +16,7 @@ WORKDIR "/src/BackOffice"
 RUN dotnet publish "BackOffice.csproj" -c Release -o /app/publish
 
 # Runtime stage - nginx for Blazor WebAssembly
-FROM nginx:alpine AS final
+FROM 194.5.195.53:32082/library/nginx:alpine AS final
 WORKDIR /usr/share/nginx/html
 
 # Remove default nginx files