ci: add CodeQL analysis

[saagpatel]

What

• Adds a CodeQL workflow for Python, JavaScript, and TypeScript analysis.
• Runs on pull requests, pushes to the default branch, manual dispatch, and a weekly schedule.

Why

• Security Review flagged this repo as missing code scanning coverage.

How

• Uses GitHub's CodeQL action with least-privilege workflow permissions.

Testing

• GitHub PR checks.

Performance Impact

• None expected outside CI runtime.

Risk / Notes

• Config-only change. If CodeQL surfaces findings after merge, handle them in a follow-up PR.

[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.