[NPM Scripts] Subfolders in src/assets are ignored

[ryansalerno]

We've done this on purpose, but we're not sure about it....

Nested folders won't get passed along to lib (either compressed, or as an untouched pass-along). Globbing should be fairly trivial to add to the logic, but we liked the simplicity of the flat structure.

But maybe there's value in copying folders to lib without touching them, so we can do fonts or any hand-tooled files. Or maybe there are good use cases for organizing asset files into subfolders that we're not thinking of or discounting.

This issue is for discussion and to acknowledge the general unease of the assets folder as it is currently set up.