Add GitHub Copilot setup steps workflow for .NET 9 environment

[Copilot]

This PR adds a GitHub Actions workflow that sets up the development environment for GitHub Copilot coding agents to work with .NET 9, matching the existing devcontainer configuration.

Changes Made

• Created .github/workflows/copilot-setup-steps.yml workflow file
• Configured the workflow to use .NET 9.0.x SDK via actions/setup-dotnet@v4
• Added verification steps to confirm .NET installation
• Used the required job name copilot-setup-steps for proper Copilot recognition
• Configured appropriate triggers: workflow_dispatch, push, and pull_request on workflow changes
• Set minimal permissions (contents: read) for security best practices

Workflow Features

The workflow ensures GitHub Copilot coding agents have access to:

• .NET 9 SDK environment matching the devcontainer setup
• Proper verification of the .NET installation
• Consistent development environment across agent sessions

Testing

• YAML syntax validated with yamllint
• Workflow structure verified against GitHub Actions standards
• Job name and trigger configuration confirmed per GitHub Copilot documentation

This provides GitHub Copilot with the same .NET 9 environment that developers get when using the devcontainer, ensuring consistent coding assistance.

Fixes #5.

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[Geertvdc]

instead of doing these steps can we use container: instead that uses our devcontainer? this already contains .net 9

[Geertvdc]

Can't we use the dev container instead of steps that install .net every time?

[Copilot]

Yes, good point! Updated the workflow to use the devcontainer image instead of manually installing .NET every time. The workflow now uses container: mcr.microsoft.com/devcontainers/dotnet:1-9.0-bookworm which matches the devcontainer setup. Commit: 825e266

[Copilot]

instead of doing these steps can we use container: instead that uses our devcontainer? this already contains .net 9

Changed the workflow to use container: with the same devcontainer image (mcr.microsoft.com/devcontainers/dotnet:1-9.0-bookworm) instead of installing .NET manually. This eliminates the redundant installation steps since the container already includes .NET 9. Commit: 825e266

[Geertvdc]

ship it! 🚀