PreMiD/Activities — reverse-engineered prompt

I want this repo set up so I can quickly make and test a new PreMiD Activity that shows what someone is doing on a website in their Discord presence. Please get the project running, make sure the built in CLI works, and use it to create a clean starter activity I can build from. Then wire up the normal development flow so it watches my changes, rebuilds automatically, and works with the PreMiD browser extension when Activity Developer Mode is turned on.

Please follow the patterns used in the existing activities, make sure the activity metadata, images, and validation checks all pass, and fix anything needed so it feels ready to submit back to the main repo. When you are done, leave me with a very simple explanation of what you changed, how I start the dev mode, and how I test the activity on the website in real time. If anything is unclear, look up the current PreMiD docs online.