add: some request concerning the admin ui

- Get the data of an event : libelle, date, duration, price, state, description
- Edit the state of an event : state (create a dto for this I guess)

Start by locating the event-related request entry points and the existing event model or DTOs. Check how event data is currently exposed and how state changes are handled, then define the response and state update scope from the issue. Done means an admin can retrieve an event's libelle, date, duration, price, state, and description, and edit its state.

Written by the indexing model from the issue text.