Dedicated Architecture Documentation

[josephbirkner]

It's crucial to document the workings of the viewport-driven update mechanism, given its complexity and involvement of multiple components and inter-process communication. This system also handles event cancellations for incoming viewport updates and requires proper request tracking. Understanding the lifetime management of various data representations—like features, attributes, and GLTF representations —is equally important. I envision a high-level overview that outlines these key behavioral aspects, serving as an entry point with references to the source code. This will equip potential contributors with a foundational understanding of the essential concepts before diving deeper into the codebase. Currently, there is only a (partially outdated) UML in the main README.