Enhancement: Confirm dialog for deleting repeater items/blocks

[bobbwal]

Summary

Add a confirmation dialog when deleting repeater items or content blocks in admin content forms.

Motivation

Accidental deletions are easy when working with repeaters/blocks, especially in long forms. A confirm dialog provides a
safety net and matches existing confirmation patterns in the admin UI.

Proposed behavior

• Clicking delete on a repeater item shows a modal:
  • Title: “Delete Item”
  • Message: “Are you sure you want to delete this item? This action cannot be undone.”
• Clicking delete on a content block shows a modal:
  • Title: “Delete Block”
  • Message: “Are you sure you want to delete this block? This action cannot be undone.”

Affected areas

• Admin content form: repeater items (array fields)
• Admin content form: block list (content blocks)

Testing

• Manual UI check in content editor: delete item/block triggers confirm modal and only deletes on confirm.