Add Example Tutorial

Start from the Nx React app generator. Land at examples/react/<slug>/. Then slim the generated lab to the one scenario this tutorial teaches. examples/react/basic-chat and docs/tutorials/basic-chat.md show a finished public example. Do not copy that app. Use the generator as the starting tree.

Load docs, simple-english, and i-have-adhd before writing tutorial pages. Load pr-description before gh pr create and after an agent push on an open PR.

End state

• App at examples/react/<slug>/ (not examples/<slug>/, not examples/ts-*).
• pnpm-workspace.yaml includes examples/react/*.
• Tutorial at docs/tutorials/<slug>.md on "tab": "tutorial".
• Examples tab child framework/react/examples/<slug> in docs/config.json.
• Overview / Quick Start (and any recipe) point at the tutorial.
• GitHub link at the bottom: https://github.com/TanStack/ai/tree/main/examples/react/<slug>.
• Live sandbox comment on the tutorial page.
• One PR on this repo.

1. Shape the app