Deprecate Flash component in primer/react

[llastflowers]

Relates to https://github.com/github/primer/issues/5437

Changelog

Changed

Deprecate the Flash component and move to @primer/react/deprecated

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

[changeset-bot]

🦋 Changeset detected

Latest commit: cf7f35c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/react	Minor

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[github-actions]

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[Copilot]

Pull request overview

This PR deprecates the Flash component in @primer/react, and exposes it via the @primer/react/deprecated entrypoint to guide consumers toward migration (notably toward Banner).

Changes:

• Added @deprecated JSDoc annotations to Flash and FlashProps.
• Marked Flash docs metadata as deprecated and updated docs import path to @primer/react/deprecated.
• Exported Flash from the @primer/react/deprecated entrypoint and updated the export snapshot.

Show a summary per file

File	Description
packages/react/src/Flash/Flash.tsx	Adds @deprecated annotations to surface deprecation warnings in TS/editor tooling.
packages/react/src/Flash/Flash.docs.json	Marks Flash as deprecated in docs metadata and points imports to @primer/react/deprecated.
packages/react/src/deprecated/index.ts	Adds Flash to the deprecated entrypoint exports.
packages/react/src/tests/snapshots/exports.test.ts.snap	Updates the deprecated entrypoint export snapshot to include Flash.

Review details

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Suppressed comments (1)

packages/react/src/Flash/Flash.tsx:17

• Same as above: add the new @primer/react/deprecated import path to the component-level @deprecated message so the warning is actionable for consumers.

/**
 * @deprecated Use `Banner` instead.
 */

• Files reviewed: 4/4 changed files
• Comments generated: 3
• Review effort level: Lite