Document React Suspense panel

[aurorascharff]

Summary

• document how to open the Canary React DevTools Suspense panel
• explain the boundary map, suspension causes, fallback preview, reveal timeline, and boundary filter
• add a focused runnable example for each panel feature
• add the page to the React DevTools reference navigation

Screenshots

Initial light-mode captures are included for the overview, boundary map, and suspended-by inspector. The remaining image references are placeholders, including all dark-mode variants, and should be replaced before marking this PR ready.

Validation

• repository pre-commit checks
• yarn prettier --check src/content/reference/dev-tools/react-suspense-panel.md src/sidebarReference.json
• yarn lint-heading-ids
• local page rendered successfully
• all five screenshot demo states rendered and were inspected with React DevTools in Chrome

[github-actions]

Size changes

Details

📦 Next.js Bundle Analysis for react-dev

This analysis was generated by the Next.js Bundle Analysis action. 🤖

One Page Changed Size

The following page changed size from the code in this PR compared to its base branch:

Page	Size (compressed)	First Load
/[[...markdownPath]]	130.04 KB (🟡 +16 B)	245.19 KB

Details

Only the gzipped size is provided here based on an expert tip.

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