ci(release): add Docker Scout compare against latest tag

[steilerDev]

Summary

• Adds an informational compare,recommendations Docker Scout step to the docker-build job (amd64 only).
• Runs while :latest still points to the previously published image, so the diff is meaningful on every release (the existing scout job runs after the docker manifest job re-tags :latest, so adding the compare there would compare the image to itself).
• Guarded with github.actor == 'steilerdev' so bot-triggered releases (Dependabot, auto-fix) skip the step.
• Pinned to docker/scout-action@v1.20.4 to match the existing scout step.

Test plan

• On the next beta release, verify the new "Docker Scout compare to latest" step appears in the Docker Build (linux/amd64) job and produces a comparison summary.
• Confirm the step is skipped when a release is triggered by Dependabot or the auto-fix bot.

[github-actions]

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