Fix relationship between typography, Material, and Neon

Currently, all typography variables are under Neon. However, the Material stylesheets depend on these. This breaks the modular/hierarchical relationship where Neon should depend on Material, and Material should be portable to any stylesheet system.

The issue names the typography, Material, and Neon stylesheet layers but does not identify files or tests. Start by locating those SCSS definitions and their imports or dependencies; done means typography is organized so Material remains portable and the dependency direction matches the stated hierarchy.

Written by the indexing model from the issue text.