Add CodeQL scanning

[jason-allen-oneal]

Summary

• add GitHub-native CodeQL analysis for JavaScript and TypeScript
• scan pushes and pull requests targeting main
• run a weekly scheduled analysis
• use least-privilege permissions and immutable action SHAs

Validation

• workflow YAML parsed successfully
• git diff --check passed

[github-advanced-security]

You are seeing this message because GitHub Code Scanning has recently been set up for this repository, or this pull request contains the workflow file for the Code Scanning tool.

What Enabling Code Scanning Means:

• The 'Security' tab will display more code scanning analysis results (e.g., for the default branch).
• Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results.
• You will be able to see the analysis results for the pull request's branch on this overview once the scans have completed and the checks have passed.

For more information about GitHub Code Scanning, check out the documentation.

[morrow-bluedot]

Independent exact-head review passed: workflow-only diff, immutable verified action SHAs, least privileges, correct JavaScript/TypeScript configuration, and all hosted checks green.