Add optional AI agent rules to React plugin template

[shaealh]

What changed

• Ask whether AI agent coding rules should be included when bootstrapping a React plugin.
• Add tool-agnostic rules covering Airflow plugin integration, React and TypeScript practices, and testing.
• Document how to adapt the generated rules for Cursor, GitHub Copilot, and other tools.
• Add tests for both opt-in and default opt-out behavior.

Testing

• uv run --frozen --project scripts pytest scripts/tests/test_react_plugin_bootstrap.py -xvs
• Airflow commit hooks passed, except lychee-docker, which was skipped because Docker was unavailable.
• Manually verified both the opt-in and default opt-out bootstrap flows.

closes: #53748

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Was generative AI tooling used to co-author this PR?

• Yes (OpenAI Codex)