eclipse-theia/theia ? reverse-engineered prompt

Build me a working Eclipse Theia based IDE starter that I can run in the browser and as a desktop app.

I want it to feel like a modern code editor, with a file explorer, editor tabs, search, terminal, and a clean welcome screen. It should be easy to extend later with plugins and custom tools, and it should support VS Code style extensions if possible. Please make sure the app starts cleanly, the main screens are wired up, and the basic developer experience is in place so I can open a workspace and edit files right away.

If anything needs a current setup detail, look up the latest docs online and use the recommended approach. Also make sure the project is organized so it is easy to run, test, and package for desktop if I want that later.