fix(transformer-directives): honor the deprecated varStyle option - #5305

Description

resolveApplyVariables computes applyVariable from varStyle and then overwrites it unconditionally on the very next line:

if (applyVariable === undefined) {
  if (varStyle !== undefined)
    applyVariable = varStyle ? [`${varStyle}apply`] : []
  applyVariable = ['--at-apply', '--uno-apply', '--uno']   // always wins
}

So the varStyle option has no effect at all. It is deprecated but still public and typed false | string:

varStyle: '--my-'  ->  ["--at-apply","--uno-apply","--uno"]   expected ["--my-apply"]
varStyle: false    ->  ["--at-apply","--uno-apply","--uno"]   expected []

varStyle: false is documented as the way to turn off custom-property @apply entirely, and it currently leaves all three defaults active.

Change

The default assignment moves into an else, so it only applies when varStyle is not provided. applyVariable still takes precedence over varStyle, which is the documented order.

Tests

A new apply variables block covering the defaults, varStyle as a string, varStyle: false, and applyVariable winning over varStyle. Reverting only the source and keeping the tests fails with expected [ Array(3) ] to deeply equal [ '--my-apply' ]; restored, the transformer-directives suite passes 78/78 and eslint is clean.