[SUBTASK]-Create group action index page

[SturmDerLiebe]

Ressources

• Group action screen: https://www.figma.com/design/q5QkaCsXuGn3XACfOWjdHa?node-id=455-17202#1139280759

Tasks

1. Create the Group Action Screen in app/group/action/page.tsx
2. Try to mimic the App Design to a reasonable extend, since on Desktop and MobileWeb some things feel better if combined on one screen.
   1. Orientate yourself on the app/authentication/page.tsx screen