[playground] react, react-dom and @fluentui/* should be peerDependencies

[dalbrx-nitrobox]

@typespec/playground@0.17.1 declares react/react-dom (^19.2.8) and exact
@fluentui/react-components@9.74.3 / @fluentui/react-icons@2.0.333 as regular
dependencies and has no peerDependencies at all (@typespec/html-program-viewer@0.86.0
does the same).

If a consuming app pins a different exact version — e.g. react@19.2.7 or
@fluentui/react-components@~9.73.8 — npm installs a nested second copy under
node_modules/@typespec/playground/node_modules/. The app then renders nothing and the console
shows:

Invalid hook call. Hooks can only be called inside of the body of a function component.
...
3. You might have more than one copy of React in the same app
Uncaught TypeError: Cannot read properties of null (reading 'useState')

Declaring react, react-dom and the Fluent UI packages as peerDependencies (with a permissive
range) would make a duplicate installation impossible and let consumers control the versions.

### Checklist

- [x] Follow our [Code of Conduct](https://github.com/microsoft/typespec/blob/main/CODE_OF_CONDUCT.md)
- [x] Read the [docs](https://typespec.io/docs/).
- [x] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[github-actions]

🎯 Issue Triage

@typespec/playground and @typespec/html-program-viewer install their own React and Fluent UI dependencies when consumer versions differ, producing multiple React instances and an invalid hook call that prevents rendering.
Category: Bug
Area: ui:playground

⚠️ No reproduction provided. A minimal repro would help diagnose this issue.

🔍 Analysis

The failure affects consumers embedding the published playground UI. Because React, React DOM, and Fluent UI are regular dependencies, npm can place incompatible copies beneath the package; React hooks then execute against a different React singleton than the renderer. The package manifests and supported peer-version ranges for both @typespec/playground and @typespec/html-program-viewer should be reviewed together.

Searches found no existing issue describing this same runtime dependency duplication. #1843 is related only as general peer-dependency authoring guidance and does not track the playground/React failure.

📝 Suggested next steps

• Provide a minimal consuming app with pinned React and Fluent UI versions that demonstrates the blank render and console error.
• Confirm supported React and Fluent UI peer ranges for both affected packages.
• Add a packaging or consumer integration test that detects nested React installations.

Generated by Agentic Triage