Delete group warning modal

A modal currently appears when deleting a group, but it might be helpful to clearly indicate that the group is linked to X hosts and that these hosts will no longer be associated with the group once it’s deleted.

<img width="509" height="270" alt="Image" src="https://github.com/user-attachments/assets/bcafb337-a04f-456c-9068-f51d0b553ce4" />