ci: update CodeQL config

[dmcilvaney]

In parallel to this we should ensure that CodeQL is configured in the repo settings.
I think we probably want to set it to fail on warnings (we are effectively green with one tiny exception, so may as well keep it that way).

• Ensure codeQL is configured to use the new yaml
• Enable Code quality (https://docs.github.com/en/code-security/concepts/about-code-quality)
• Set branch rules to require the check
• Set failure severity
• Fix outstanding issue in magefile completions.go

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[Copilot]

Pull request overview

Updates the repository’s CodeQL GitHub Actions workflow to use the newer “advanced” configuration template, expanding analysis beyond Go and adopting the newer build-mode-based setup.

Changes:

• Switch workflow to “CodeQL Advanced” template structure and defaults (including top-level permissions: {}).
• Expand the matrix to analyze actions, go, and python, with per-language build-mode.
• Update CodeQL action pins to v4.36.2 and configure query suites (security-extended,security-and-quality).

[Copilot]

Pull request overview

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