ci(compatibility): require explicit risk acceptance

[SDAChess]

Summary

Compatibility reviews currently mark documented intentional changes as ACKED without linking explicit acceptance of the consumer risk, and repeat unchanged findings on successive revisions. Require an acceptance-comment or review URL, show plain-language acceptance status, and post only new or materially updated findings while retaining the complete assessment in the artifact.

Related Issue

Closes #4594

The linked issue has no state:accepted label; the PR author has verified ADMIN access to NVIDIA/OpenShell.

Changes

• Require explicit acceptance of the specific break and consumer risk; descriptions, test authorization, general approvals, and previous bot claims do not qualify. Display a direct comment link without quoting it.
• Read every page of PR discussion before finalizing findings. Preserve previous-comment links for unchanged findings and omit those findings from new PR comments.
• Set reasoning effort to high and limit the prompt to breaking changes to existing public contracts, retaining existing compatibility evidence requirements.
• Validate report links, retain both full and comment-only Markdown artifacts, and update the contributor CI guidance.

Testing

• Checks appropriate to the affected code and behavior pass
• Unit tests added/updated (omitted as requested)
• E2E tests added/updated (not applicable to this CI reporting change)

Passed: Ruff lint and formatting, actionlint for both affected workflows, JSON schema field consistency, and git diff --check.

A live model review was not run. Interpreting explicit acceptance and matching prior findings still depend on the reviewer; validation enforces the presence and shape of associated PR discussion links.

The local pre-commit hook failed while preparing Node/Python tooling on NixOS and was skipped with explicit author approval; the focused checks above passed separately.

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (not applicable; contributor CI skill updated)