Elizabethvk/Shared-Clipboard ? reverse-engineered prompt

Build me a PHP web app for a shared clipboard system where people can save and share things like links, text, code, and images between browsers.

I want users to be able to create or join different clipboards, some public and some private, with admins defining what each clipboard accepts and what can be pasted out of it. For example, one clipboard could allow only images, another could support text, links, PHP, JavaScript, or zipped source code. Let users paste content, upload files when needed, see their clipboard history, and get notified when something new is added, either by email or inside the app. It should also support one time or timed sharing, like 30 minutes, 8 hours, or single use access.

Please include simple admin tools for grouping clipboards, viewing stats, and importing or exporting clipboard types and data. Also add a few demo PHP pages that simulate external systems creating clipboard types, sending content into the system, and watching for new paste events. If you need current best practices, look up the latest docs online.