Fix role getting unselected when changing write

[Arnei]

Fixes #1507.

There is a bug in the access policy tab of event details that can be reproduced like so:

1. Add a new policy.
2. Set a role for the new policy.
3. Change the write rights for the new policy.

The role is now unset. This patch should fix that.

[github-actions]

Use docker or podman to test this pull request locally.

Run test server using develop.opencast.org as backend:

podman run --rm -it -p 127.0.0.1:3000:3000 ghcr.io/opencast/opencast-admin-interface:pr-1523

Specify a different backend like stable.opencast.org:

podman run --rm -it -p 127.0.0.1:3000:3000 -e PROXY_TARGET=https://stable.opencast.org ghcr.io/opencast/opencast-admin-interface:pr-1523

It may take a few seconds for the interface to spin up.
It will then be available at http://127.0.0.1:3000.
For more options you can pass on to the proxy, take a look at the README.md.

[github-actions]

This pull request is deployed at test.admin-interface.opencast.org/1523/2026-03-13_10-01-29/ .
It might take a few minutes for it to become available.

[ypatios]

thanks for this :D

[ypatios]

This pull request is deployed at test.admin-interface.opencast.org/1523/2026-03-13_10-01-29/ . It might take a few minutes for it to become available.

a quick test here confirms fix 👍
at the same time I have to note the sluggishness of that particular tab and the grave effects of #1506; see also #1442

Screen.Recording.2026-03-13.at.11.39.08.mp4