The devcontainer configuration was missing authentication setup for the private Azure DevOps NuGet feed, preventing proper package restoration when using GitHub Codespaces or local devcontainer development.

Problem

The existing devcontainer would fail to restore packages that depend on private NuGet packages from the Azure DevOps feed (https://pkgs.dev.azure.com/intelliTect/_packaging/EssentialCSharp/nuget/v3/index.json). This affected packages like:

• ContentFeedNuget
• EssentialCSharp.Shared.Models

Solution

This PR implements a secure interactive authentication solution using Microsoft's recommended approach for Azure Artifacts Credential Provider:

Key Changes

1. Enhanced devcontainer.json:

   • Updated to use .NET 9.0 SDK specifically
   • Added VS Code C# extensions for better development experience
   • Added post-create command for automated setup
   • Removed hardcoded environment variables for cleaner configuration

2. Interactive Authentication Setup:

   • Created setup-nuget-auth.sh script that:
     • Installs Azure Artifacts Credential Provider automatically
     • Uses dotnet restore --interactive for secure credential prompting
     • Gracefully falls back to public packages only when authentication fails
     • Provides clear user guidance for authentication options

3. Developer Experience:

   • Secure interactive authentication - no need to store PATs in files or environment variables
   • Automatic fallback to public packages when private authentication is unavailable
   • Clear user prompts and guidance during setup
   • Follows Microsoft's recommended authentication patterns

Authentication Options

Interactive Authentication: When prompted during package restoration, users can:

1. Use their Azure DevOps account credentials, or
2. Create a Personal Access Token (PAT) with 'Packaging (read)' permissions from https://dev.azure.com/intelliTect/_usersSettings/tokens

Backward Compatibility

The solution is fully backward compatible:

• Developers without private feed access can still use the devcontainer
• The setup script automatically falls back to public packages when authentication fails
• All public packages restore normally without any user interaction required

Testing

• ✅ Package restoration works without authentication (public packages only)
• ✅ Interactive authentication works for private packages
• ✅ Build and tests pass successfully
• ✅ Graceful handling of network restrictions and missing dependencies
• ✅ Secure credential handling with no storage of sensitive information

This brings the devcontainer authentication in line with Microsoft's recommended security practices while ensuring consistent development environments across local development, Codespaces, and CI/CD pipelines.

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