Add pinned PR CI security baseline

[dejaguarkyng]

Summary

• add pinned PR CI that calls the Jungle Grid reusable Node workflow
• run the repository's real npm lint and build scripts
• add CodeQL analysis for JavaScript/TypeScript and weekly Dependabot updates for GitHub Actions and npm

Validation

• git diff --check
• Ruby YAML parse for workflow and Dependabot files
• python3 -m json.tool package.json
• Node/npm commands were not runnable in the local environment because node/npm are not installed; GitHub Actions will run npm ci, npm run lint, and npm run build

Security

• least-privilege workflow permissions
• no secrets are passed to PR CI
• no deployment workflow or production credentials are introduced
• external actions and reusable workflow calls are pinned to full commit SHAs

[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.