[CI] Add `ls-lint`: An extremely fast directory and filename linter - Bring some structure to your project filesystem

https://github.com/loeffel-io/ls-lint

https://ls-lint.org/

https://ls-lint.org/2.2/getting-started/installation.html

Lots of ways to install and use `ls-lint` and they also have a GitHub Action.

Start by reading the linked ls-lint installation and GitHub Action documentation, then inspect the repository's existing CI configuration. The issue does not name a configuration file or directory rules; completion would require adding ls-lint to CI and defining the filesystem checks to run.

Written by the indexing model from the issue text.