A browser extension for Safari that makes sure that cut, copy, and paste are enabled.
This is pretty rough and does work. The vast majority of the files in here are boilerplate needed for either the WebExtension standard or the macOS/iOS application that the extension must be bundled inside of.
Shared (Extension)/Resources/ is the actual extension. content.js is what gets injected into the page.
In Safari, you need to enable "Allow Unsigned Extensions" in the Develop menu. You must do this every time Safari starts.
To test, first run bin/test-server in Terminal. Then, go to http://localhost:8000 and try the various test cases. You have to do this because <all_urls> in Safari doesn't actually match all URLs; Safari doesn't allow extensions to run against file: URLs.