camunda/camunda-bpm-platform ? reverse-engineered prompt

Build me a Java workflow automation platform like Camunda 7, with a BPMN process engine at the core that can run inside a Java app and also expose a REST API for starting and managing processes.

I want the basics of process execution, user tasks, and simple admin and monitoring screens so I can see running workflows and complete tasks in a browser. If it makes sense, include support for decision tables too, and make it easy to plug into Spring or other Java applications.

Please set it up so it feels like a real open source platform, with clear modules for the engine, REST, web apps, and test support. Use the existing docs and current best practices if you need to look anything up online. Keep the first version focused on something usable end to end, not every advanced feature at once.