Add Blazor and React versions of the QR Code topic

[ChronosSF]

Task type

• New topic / component documentation
• Update existing topic (new release, API change, new feature)
• Add missing platform variant (Angular / React / WebComponents / Blazor)
• Improve existing content (clarity, examples, structure)
• Add or update code samples
• Other

Platform(s)

• Angular
• React
• WebComponents
• Blazor
• All platforms

Description

The QR Code will be released for Blazor and React at a later date. When it ships, the QR Code topic needs to cover both platforms.

The topic in #837 covers Angular and Web Components for now: its entry in docs/xplat/src/content/en/toc.json excludes React and Blazor. It already has draft React and Blazor PlatformBlocks, and it embeds the shared /inputs/qr-code/* samples for React and Blazor. Most of the work is checking that content against the released API and removing the TOC exclusions.

Three parts are still Angular and Web Components only: the Export section, the Methods table (toImage(), toBlob()), and the cross-origin logo item in Known Limitations.

Acceptance criteria

• React and Blazor are removed from the QR Code exclude list in docs/xplat/src/content/en/toc.json.
• The React and Blazor code snippets (installation, registration, and usage) match the released API.
• If React and Blazor expose toImage() and toBlob(), the Export section, Methods table, and export limitation have React and Blazor versions.
• Every embedded /inputs/qr-code/* sample exists for React and Blazor and loads in the built topic.
• The API References section and all ApiLinks resolve for React and Blazor.

Related resources

• Docs PR: feat(qr-code): add docs #837
• Topic: docs/xplat/src/content/en/components/inputs/qr-code.mdx