fix: add missing jest-preset.js export

[mdjastrzebski]

Summary:

The new @react-native/jest-preset package did not include critical jest-present.js file in the exported version: https://www.npmjs.com/package/@react-native/jest-preset?activeTab=code

Without this the new preset is not usable, and the old preset is no longer available (in nightly versions)

Changelog: [Internal]

Test Plan:

[huntie]

Updated summary to Changelog: [Internal], since this fixes an unreleased feature.

[meta-codesync]

@huntie has imported this pull request. If you are a Meta employee, you can view this in D93727883.

[cortinico]

Review automatically exported from Phabricator review in Meta.

[meta-codesync]

@huntie merged this pull request in 55984e2.

[react-native-bot]

This pull request was successfully merged by @mdjastrzebski in 55984e2

^{When will my fix make it into a release? | How to file a pick request?}

[m-bert]

Was it included in 0.85.0-rc.0? Here I can see that it should be, but when I create new app with npx @react-native-community/cli init jest-preset.js is still missing.

[huntie]

@m-bert Yes I believe so.

cc @alanleedev in case there's any release integration issue with this (e.g. template).

[m-bert]

Yes I believe so.

In that case I don't know why it doesn't work in my case. It also caused our test CI to fail. Is there anything else that I should do, other than steps from upgrade helper?

[m-bert]

Oh okay, I think I've found what's wrong.

Default template does not include @react-native/jest-preset in package.json and when I tried to install it via yarn it added 0.85.0-nightly-20260219-44901aaf9 version which doesn't contain jest-preset.js.

Same with upgrade helper, it doesn't say that jest-preset should be added.