Bump ai from 3.3.25 to 4.0.9

Bumps [ai](https://github.com/vercel/ai) from 3.3.25 to 4.0.9.
- [Release notes](https://github.com/vercel/ai/releases)
- [Changelog](https://github.com/vercel/ai/blob/main/CHANGELOG.md)
- [Commits](https://github.com/vercel/ai/compare/ai@3.3.25...ai@4.0.9)

---
updated-dependencies:
- dependency-name: ai
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>