## Summary
- Bump React DevTools from 7.0.1 to 8.0.0 (packages + extension
manifests only; no publish).
- `scripts/devtools/prepare-release.js` only supports minor/patch, so
this major bump is manual.
- Changelog is curated from DevTools commits since 7.0.1 (features vs
bugfixes; internal/test-only changes omitted).

## Test plan
- [ ] Confirm published package versions would be 8.0.0 for
`react-devtools`, `react-devtools-core`, and `react-devtools-inline`
- [ ] Confirm Chrome/Edge/Firefox extension manifests show 8.0.0
- [ ] Review `packages/react-devtools/CHANGELOG.md` 8.0.0 section for
accuracy before undrafting