npm run build-lib does not copy assets when run on Windows

[csiew]

Problem

Running npm run build-lib to build the library from source on Windows will not copy style and font assets to the dist/ directory.

Probable cause

build script in package.json directly references Bash commands. This will only run on macOS and Linux, but not on Windows.

Steps for reproducibility

1. Clone the repository locally and install dependencies with npm install.
2. Run npm run build-lib and then view the output in the dist/ directory.