Unbundle does not emit .css imports #842
Description
Reproduction link or steps
https://github.com/RobinVdBroeck/tsdown-unbundle-css-bug
What is expected?
When using unbundle: true with css.inject: true, we should get import "stylesheet.css" in dist aswel. However, this is not the case.
CSS modules do not seem to have this problem.
What is actually happening?
In the example, button gets renamed to button2.js in the dist folder, the css import is dropped.
Any additional comments?
css.splitting should default to true if unbundle: true, now defaults to false.
This use case for this is tree shaking, since we would like vite (or another build tool) to be able to drop the css for components that are not imported in the final product.