trigger-corp/weather-app-demo — reverse-engineered prompt

Build me a simple mobile weather demo app based on this project.

I want a basic weather app that can run from an HTML, CSS, and JavaScript codebase, with a clean small screen layout for a phone. It should let the user check the weather using a Weather Underground API key from the config, then show the current weather in a clear way. Keep it simple and close to a demo app, not a big production product.

Please set it up so it works with the existing Trigger.io style project and can be built and tested in the mobile emulator. If any old API details or Trigger.io docs are out of date, look up the current docs online if you need to and make the smallest reasonable updates. Keep the code easy to understand so someone learning from the demo can follow it.