Add CodeQL

[martincostello]

Changes

Add GitHub Actions workflow to run CodeQL for GitHub Actions and C#.

Merge requirement checklist

• Unit tests added/updated
• CHANGELOG.md updated
• Changes in public API reviewed (if applicable)

[github-advanced-security]

This pull request sets up GitHub code scanning for this repository. Once the scans have completed and the checks have passed, the analysis results for this pull request branch will appear on this overview. Once you merge this pull request, the 'Security' tab will show more code scanning analysis results (for example, for the default branch). Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results. For more information about GitHub code scanning, check out the documentation.

[Copilot]

Pull Request Overview

This PR adds a GitHub Actions workflow to implement CodeQL security analysis for the repository, scanning both GitHub Actions workflows and C# code.

• Introduces automated security scanning with CodeQL for Actions and C# languages
• Configures the workflow to run on push/PR to main branch, weekly schedule, and manual dispatch
• Implements a status reporting job to provide clear feedback on scan results

Comments suppressed due to low confidence (1)

.github/workflows/codeql.yml:1

• [nitpick] The workflow name 'codeql' should follow consistent naming conventions. Consider using 'CodeQL' or 'CodeQL Analysis' for better readability and consistency with GitHub's naming conventions.

name: codeql

[martincostello]

Will fix up anything it flags post-merge.