Postcss + async rules doesn't work well

[DarkHole1]

UnoCSS version

0.59.0

Describe the bug

@unocss/postcss doesn't replaces @apply with rule contents on a certain conditions:

• Source extractors didn't found class (probably)
• File has @unocss directive
• Rule is async

The problems comes from here:

unocss/packages/postcss/src/apply.ts

Lines 11 to 12 in 5ae78df

	// @ts-expect-error types doesn't allow async callback but it seems work
	root.walkAtRules(directiveName, async (rule) => {

I tried patching package locally and awaiting all functions something like that:

let promises: Promise<unknown>[] = [];
root.walkAtRules(directiveName, (rule) => {
    promises.push((async () => {
        // ...
    })())
});
await Promise.all(promises);

And this fixes it.

Reproduction

https://github.com/DarkHole1/uno-postcss-bug

System Info

No response

Validations

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• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
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• The provided reproduction is a minimal reproducible example of the bug.

[antfu]

Would you like to send a quick PR? Thanks