Onboard OpenHands

[neubig]

• A human has tested these changes.

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Why

Issue #133 asks us to onboard this repository for OpenHands by following the setup-openhands skill.

Summary

• add .openhands/setup.sh and .openhands/pre-commit.sh so OpenHands sessions bootstrap dependencies and run the repo's fast CI checks before committing
• rename the PR review workflow to .github/workflows/pr-review.yml and align it with the current OpenHands example workflow
• expand AGENTS.md with the install and validation commands used by the onboarding automation

Issue Number

Closes #133.

How to Test

• bash -n .openhands/setup.sh .openhands/pre-commit.sh
• ./.openhands/setup.sh
• ./.openhands/pre-commit.sh
• npx prettier --check .github/workflows/pr-review.yml

Video/Screenshots

N/A

Type

• Bug fix
• Feature
• Refactor
• Breaking change
• Docs / chore

Notes

• This PR was created by an AI agent (OpenHands) on behalf of the user.
• The fast pre-commit checks mirror .github/workflows/ci.yml; Docker-backed integration coverage remains in .github/workflows/integration-tests.yml.

@neubig can click here to continue refining the PR