genius257/DllStructEx ? reverse-engineered prompt

Build me an AutoIt3 helper library that extends DllStruct so it feels more like C style structs.

I want it to let me create structs and also get back the original struct definition string later, which normal DllStruct does not seem to do. It should support unions and nested structs too, so I can model more complex native data layouts without a lot of manual work.

Please include a simple example script that shows how to define a struct, read and write fields, use a union, and nest one struct inside another. If there are any tricky parts or limits because of how AutoIt works, keep the behavior clear and predictable.

If you need to check current AutoIt docs or examples online to match the language properly, go ahead and do that. Also add a small test or demo file if that helps show the main features working.