joustingmatch/ObsidianUltra ? reverse-engineered prompt

Build me the Obsidian UI Library for Roblox in Luau, with a clean set of reusable UI components that are easy to drop into a game. I want it to feel polished and consistent, with sensible defaults, good spacing, and support for styling and themes so the UI can be reused across different screens.

Please make sure there is a simple example showing how to create a window or panel, add a few common controls, and update them at runtime. Keep the code organized so it is easy to extend later, and include whatever helper code is needed to make the library pleasant to use.

If you need clarification on the intended behavior, check the documentation site linked in the README and look up any current Roblox UI details online if needed.