Build reviewed-change history under branch protection

[Felix-Zuo]

Scope

Close the remaining CodeReviewID Scorecard alert by accumulating reviewed pull requests under the new branch protection policy.

Current State

Branch protection is now enabled on main with required PR review, required conversation resolution, and required CI/Security checks. Scorecard currently reports Found 0/29 approved changesets.

Acceptance Criteria

• Future changes merge through reviewed PRs rather than direct pushes
• The repository accumulates enough approved changesets for Scorecard to pass the Code-Review check
• Alert reference: https://github.com/Felix-Zuo/HulunGuard/security/code-scanning/16