Agent host: assess review comments before assisted approval

[Benjamin Christopher Simmonds (benibenj)]

Summary

• supplement Copilot's existing assisted-approval judge with the exact untrusted PR and code-review comments
• require both the SDK policy and the comment-specific safety assessment to permit automatic submission
• bind assisted approval to a fingerprint of the reviewed comments so changed comments are reassessed
• fall back to the existing interactive picker on unsafe, unavailable, invalid, oversized, or timed-out assessments
• surface assisted-approval reasons through the existing risk-assessment UI

Stack

• Depends on Agent host: submit auto-approved review comments #329592
• Base branch: benibenj/agents/investigate-comments-reveal-issue

Testing

• Reviewed twice with the Opus 5 rubber-duck reviewer and addressed its findings.
• Final validation has not been rerun after the last review fixes.