Enable repository security workflows

[premsathisha]

What changed

• Add Dependency Review for pull requests.
• Add scheduled, push, and pull-request CodeQL analysis for Swift and JavaScript.
• Update docs/REPO MAP.md to document the new security workflows.

Why

The repository security settings were audited against GitHub's six-maintainer-settings guidance. GitHub-side controls are enabled separately; these workflow files provide the repository-side dependency review and CodeQL coverage.

Validation

• git diff --check
• Ruby YAML parsing for both workflow files

The repository's main branch is protected and requires one approving review.

[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.