www/tailwindcss4: Improve loader & inject default NODE_PATH

Double-bump PORTREVISION because a private one is in use in some places.

Update a bunch of flags that broke in the latest npm update.

This simplifies most use cases to just modify the tailwind calling path,
and as a bonus it makes the testing simpler too. Most of the tests are
failure cases identified during using tailwind against
https://phoenixframework.org/ testing.

Sponsored by: SkunkWerks, GmbH
Event: EuroBSDcon 2026