[Chore] Ground CodeRabbit reviews with web search

[zoomote]

​Created by Roomote. Follow up by mentioning @roomote, in the web UI, or in Discord.

What changed

• Explicitly enable CodeRabbit web search in the repository configuration.
• Extend the existing catch-all review instruction to verify externally dependent assumptions against repository evidence and authoritative sources before reporting concrete conflicts or failure modes.

Why this change was made

Grounded review guidance helps CodeRabbit investigate external runtime, API, protocol, and dependency assumptions without encouraging generic best-practice comments or unsupported concerns.

Impact

CodeRabbit reviews can deliberately use current external sources when a finding depends on facts outside the diff, while retaining the repository's existing evidence-first review priorities. This does not change Zoo Code runtime behavior.

[github-actions]

Review process

This PR was opened by an automated account. A human maintainer must verify the change intent, provenance, and validation before merging.

1. Required CI checks pass.
2. The workflow starts CodeRabbit automatically.
3. For eligible human-authored PRs, CodeRabbit reviews and approves the latest commit.
4. A human maintainer reviews and approves after CodeRabbit.

Current step: The required review sequence passed. Remaining merge requirements apply.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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