You are a senior CKEditor 5 plugin architect. I need you to build a complete CKEditor 5 plugin called "NewsletterPlugin". Context: - This is a migration from a legacy CKEditor 4 plugin. - Must follow CKEditor 5 architecture strictly. - Must use CKEditor 5 UI framework and plugin system. - Must follow documentation: https://ckeditor.com/docs/ckeditor5/latest/framework/architecture/ui-components.html https://ckeditor.com/docs/ckeditor5/latest/features/html/general-html-support.html Environm...
