Backend: glazier (Rust)

I wonder if Nuklear could interface with [Glazier](https://github.com/linebender/glazier ) (yeah, Rust) or similar to lower the barrier for both newcomers as well as seniors who must currently choose backend and then handle these os-specific things on their own.

No file, test, or entry point is named. Start by reviewing Nuklear's existing backend and OS-specific integration alongside Glazier's Rust interface. Done would require a concrete, agreed integration scope and implementation path.

Written by the indexing model from the issue text.