Bump @types/react from 19.1.11 to 19.1.12 in /landing-page (#311)

Bumps [@types/react](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/react) from 19.1.11 to 19.1.12.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/react)

---
updated-dependencies:
- dependency-name: "@types/react"
  dependency-version: 19.1.12
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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