Implement hard-delete UI for AI Catalog items and update abuse report email

Summary

Implement the hard-delete UI for AI Catalog items (as designed in #579029 (closed)) and update the abuse report email template to include instructions for using this new UI feature.

Context

From #578591 (comment 2880290899):

Once the hard-delete feature for admins is implemented in the UI, we'll need to update the email template to include these details.

Currently, instance admins can only hard-delete AI Catalog items via GraphQL mutations. We need to provide a UI-based deletion flow and update the abuse report email to guide admins to use it.

Tasks

Frontend

  • Implement hard-delete UI flow as designed in #579029 (closed)
  • Add confirmation dialog with deletion method options (soft delete vs. hard delete)
  • Ensure the feature is accessible from the AI Catalog item's overflow menu
  • Test the deletion flow for both public and private items

Backend

  • Update the abuse report email template to include UI-based deletion instructions
  • Check if this note is now satisfied: !212079 (comment 2884818512)
  • Prioritize UI instructions over GraphQL mutation examples in the email
  • Keep GraphQL mutations as an alternative method
  • Ensure email instructions match the implemented UI flow
  • Test the updated email template

Design Reference

See the UX design and specifications in #579029 (closed)

Related Issues

Edited by Florie Guibert