chore(ci): automerge 加 Harden-Runner egress audit + scorecard 周扫

[randypanding]

为什么

automerge 是全组织唯一在 runner 上接触 AGENT_APP_SECRET（App 私钥→组织级写权限）的 job。pull_request_target + secrets 组合正是 2025-2026 Megalodon/GhostAction 攻击的目标形态。

决策依据：ADR-0011（https://github.com/Cloudbird-Software/agent-registry/pull/6）

内容

1. automerge job 首步加 Harden-Runner（audit 模式），pin SHA v2.21.0
2. 新增本仓 scorecard 周扫（周一 06:00 UTC）

切 block 时的起点 allowlist

automerge: api.github.com:443, github.com:443（create-github-app-token + gh pr merge 仅此两域）

生效说明

• automerge 改动随本仓 main 即刻生效（不依赖 v1 标签）
• ci.yml 引用的 reusable workflows 的 audit 要等 CI-Workflows bump v1 后生效

[coderabbitai]

Warning

Review limit reached

@randypanding, you've reached your PR review limit, so we couldn't start this review.

Next review available in: 3 minutes

Limit details: You’ve used all 3 included reviews currently available under your plan.

Enable usage-based reviews in Billing to review now. Otherwise, wait until the next included review is available.
You're only billed for reviews past your plan's rate limits ($0.25/file).

How can I continue?

After more reviews become available, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

To avoid repeated limits, reduce automatic review volume by pausing incremental auto-reviews earlier, using label-based review opt-in, excluding WIP or generated PR titles, or requesting reviews manually when the PR is ready. If your team needs uninterrupted high-volume reviews, an organization admin can enable usage-based reviews.

How do review limits work?

CodeRabbit enforces per-developer PR review limits for each organization. Most developers receive the normal plan review availability.

For paid Pro and Pro+ PR reviews, CodeRabbit uses adaptive limits for sustained high-volume activity. When a developer's recent PR review activity reaches the 95th percentile or higher among CodeRabbit users, additional reviews become available more gradually as earlier reviews age out of the rolling window.

Please refer docs for additional details.

Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: a9d80cd0-3396-4013-a4c4-8048e2f265cf

📥 Commits

Reviewing files that changed from the base of the PR and between 817b03c and 3c7cb5d.

📒 Files selected for processing (2)

• .github/workflows/automerge.yml
• .github/workflows/scorecard.yml

---

_{Comment @coderabbitai help to get the list of available commands.}