Add CodeQL code scanning workflow

[claude]

Requested by William Storey, Greg Oschwald · Slack thread

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What: GeoIP2-ruby previously ran CodeQL via GitHub "default setup". This moves it to an advanced workflow file (consistent with the org's other repos), scanning the Ruby code with CodeQL on every pull request and weekly.

How: Adds .github/workflows/codeql-analysis.yml (languages: ruby, no build step since Ruby is interpreted, github/codeql-action v4.37.0 pinned by SHA) and a codeql group to the github-actions Dependabot ecosystem so codeql-action bumps arrive as one grouped PR (per STF-983). Default setup has been disabled on this repo so the advanced workflow's results upload cleanly.

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Generated by Claude Code

[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.