docs: explain pull request verification routing

[wolfiesch]

Summary

• document the exact lightweight and full-lane path policy
• keep verify as the stable branch-protection check
• keep exact-head review enforcement in the repository shipping command
• remove the review-event status bridge because bot-triggered runs completed as action_required without jobs

Verification

• python3 .github/scripts/test_ci_policy.py
• actionlint .github/workflows/ci.yml
• commit b52fa907d989b94bdf991df06fdf3776eb2ff4d9 exercised the fast lane: classification passed in 10 seconds, verify passed in 3 seconds, and cross-platform jobs were skipped
• the final head intentionally uses the full lane because it deletes a workflow file

[Copilot]

🟡 Changes recommended

The new documentation has a couple of factual/precision issues (fast-lane path criteria and exact-head-review publication semantics) that should be corrected to match the implemented CI policy.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Documents how AgentTab’s CI policy routes documentation-only pull requests through a lightweight verification lane, and how an exact-head automated review check is enforced via branch protection.

Changes:

• Add a “Pull request routing” section describing fast vs full verification lanes.
• Describe the exact-head-review gate semantics tied to the pull request head commit.

File summaries

File	Description
docs/verification.md	Adds documentation for CI lane routing and the exact-head automated review check behavior.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 2
• Review effort level: Lite

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[Copilot]

🟡 Changes recommended

The new routing doc references an unnamed “repository shipping command” enforcing exact-head review, which is not discoverable in-repo and should be clarified or linked.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Lite

[Copilot]

🟢 Approval recommended

The documentation matches the implemented CI lane selection and verify workflow behavior, and the removed workflow has no remaining in-repo references.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0 new
• Review effort level: Lite