Enhance CI workflow with Docker Scout

[mathieu-benoit]

Add Docker Scout comparison and improve CI workflow

[github-actions]

Overview

Image reference	score-radius:latest	score-radius:latest
- digest	444c4602140f	444c4602140f
- tag	latest	latest
- provenance	e100e09	34fe85a
- vulnerabilities
- platform	linux/amd64	linux/amd64
- size	5.3 MB	5.3 MB
- packages	39	39

Policies (0 improved, 0 worsened)

Policy Name	score-radius:latest	score-radius:latest	Change	Standing
Default non-root user	✅	✅		No Change
No AGPL v3 licenses	✅	✅		No Change
No fixable critical or high vulnerabilities	✅	✅		No Change
No high-profile vulnerabilities	✅	✅		No Change
No outdated base images	✅	✅		No Change
No unapproved base images	⚠️ 1	⚠️ 1		No Change
Supply chain attestations	✅	✅		No Change
Valid Docker Hardened Image (DHI) or DHI base image	⚠️ 1	⚠️ 1		No Change