[andreas-fahrecker]

Summary

Updates the expected CSS strings in the import directive and
plugin directive test suites (v4) to match Tailwind's documented
selector-flattening behavior. These 4 tests were failing on
unmodified main, unrelated to any other changes.

What was happening

The tests expected nested output, e.g.:

.intersect\:opacity-50 { &:not([no-intersect]) { opacity: 50%; } }

but Tailwind actually produces flat selectors:

.intersect\:opacity-50:not([no-intersect]) { opacity: 50%; }

Per the Tailwind docs on nesting,
Tailwind uses Lightning CSS to flatten nested CSS into flat selectors
so it's understood by all modern browsers, this is expected,
documented behavior, deviating from the expected strings in the tests.

Changes

• Updated the 4 expected strings in import directive / plugin directive (should add variants, should add arbitrary values)
  to the flat-selector shape Tailwind actually produces.
• No changes to the test harness, plugin source, or package.json.

Testing

All 6 tests (2 legacy v3, 4 v4) pass locally after this change.