Delegate Listing Issues

When staff users add delegates to a ticket and clients impersonate the ticket, the delegates are not displayed in their list view. This prevents clients from seeing or removing delegates added by staff, which seems incorrect.

Additionally, it's currently possible for both users and clients to invite someone with the same email address, which seems like a bug.

To address these issues, it's proposed to allow both clients and users to see the same list of delegates. Certain data, such as client name, image, and email, would be denormalized to avoid reliance on loading a client object, which is not possible in the client context.