[Task]: Revamp plugin manager example app

[elliotBraem]

Overview

The plugin manager example app is a helpful resource when developing plugins, but it is hard to extend because it is just a basic javascript and html app.

The goal is to improve it to match the style of the main curate.fun app, and make it easier to improve for more upcoming features. Watch video to see how it is used: https://devpost.com/software/curate-fun

Details

Features:

• JSON vs separate plugin customizer
• Should be able to rearrange the order of plugins
• Run transformations on content input (can be text or JSON object)
• Configure plugin registry
• Save configuration drafts

The look and ordering of the app can completely change. Let's spec it out

Acceptance Criteria

• Convert to React app, matching the tech stack of main app : https://github.com/PotLock/curatedotfun (tanstack router, tailwind) (MAINTAIN RSPACK)
• Use shadcn components, I think we could define a component library in this repository which the main app can later import
• Maintain the existing functionality but match the main apps style