kaviranga/scalable-app ? reverse-engineered prompt

Build me a simple Java Maven starter called scalable app that runs out of the box and gives me a solid base to grow from.

I want the project to be clean and easy to understand, with a basic main entry point, a sensible package structure, and a few example classes that show how to organize code for a bigger app later. Please make sure it builds and runs with Maven, and include a couple of basic tests so I know everything is wired up correctly.

Keep the setup lightweight and practical, not over engineered. If you need to check current best practices or docs online, go ahead. Also add a short README that tells me how to build and run it from a fresh clone, so someone new to the project can get started quickly.