perf(todo): Merge hot updates of uno.css to reduce the number of updates

[Simon-He95]

Clear and concise description of the problem

Every time the file magicString is updated, it will trigger a hot update of uno.css. Is it possible to find a way to merge this update, or add a delay or cancellation strategy, and only update it once for the last time?

Suggested solution

To be explored

Alternative

No response

Additional context

No response

Validations

• Read the Contributing Guidelines.
• Read the README.md of using the package.
• Already used the Interactive Docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[antfu]

We already doing a bit of throttling for sending the events. If too long it would make it feel slower to response to user changes. Do you have some case specifically to improve?

[Simon-He95]

#3741