chore(deps): bump the next-stack group across 1 directory with 3 updates

Bumps the next-stack group with 3 updates in the / directory: [next](https://github.com/vercel/next.js), [react](https://github.com/facebook/react/tree/HEAD/packages/react) and [react-dom](https://github.com/facebook/react/tree/HEAD/packages/react-dom).


Updates `next` from 15.5.18 to 16.2.6
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.5.18...v16.2.6)

Updates `react` from 19.0.0 to 19.2.6
- [Release notes](https://github.com/facebook/react/releases)
- [Changelog](https://github.com/facebook/react/blob/main/CHANGELOG.md)
- [Commits](https://github.com/facebook/react/commits/v19.2.6/packages/react)

Updates `react-dom` from 19.0.0 to 19.2.6
- [Release notes](https://github.com/facebook/react/releases)
- [Changelog](https://github.com/facebook/react/blob/main/CHANGELOG.md)
- [Commits](https://github.com/facebook/react/commits/v19.2.6/packages/react-dom)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 16.2.6
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: next-stack
- dependency-name: react
  dependency-version: 19.2.6
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: next-stack
- dependency-name: react-dom
  dependency-version: 19.2.6
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: next-stack
...

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Author: dependabot[bot]