Add forui tests

[Pante]

Adds forui (a Flutter widget library, ~3500 non-golden widget/unit tests) to the registry.

Pinned against 5968a032480a2bca48373b3402fe80c13c8e72cf which passes on Flutter main.

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• I read the [Flutter Style Guide] recently, and have followed its advice.
• I signed the [CLA].
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is [test-exempt].
• All existing and new tests are passing.

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[Pante]

For transparency, CLA failed because I included Claude as a co-author.

[Piinks]

HI @Pante thanks for contributing! This LGTM, thank you for adding tests!

[Piinks]

When this lands, flutter/flutter needs a PR to update the pinned hash for this repo.

[dkwingsmt]

RSLGTM

[Pante]

Thanks for the quick turnaround @Piinks !

When this lands, flutter/flutter needs a PR to update the pinned hash for this repo.

Gotcha, I'll open it once this PR lands.