vite: Fix CSS output not updating in watch mode

[askoufis]

Fixes #1351.
Fixes #1372.

Thanks to @szszoke for the lead.

Snapshot version: 0.0.0-fix-watch-mode-20240429115131.

While it would be nice to have some kind of fixture/integration test for vite watch mode, it would be a bit involved, so I'd prefer to ship the fix first, and look into a test later.

I wonder if this also addresses the issue that prompted #1327.

[changeset-bot]

🦋 Changeset detected

Latest commit: e8f4e13

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@vanilla-extract/vite-plugin	Patch
@vanilla-extract-private/test-helpers	Patch
@vanilla-extract-private/tests	Patch

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[szszoke]

Is there an easy way to test this? I suppose it would be quite simple to just make changes in this PR to the files in your local node_modules directory.

[askoufis]

Is there an easy way to test this? I suppose it would be quite simple to just make changes in this PR to the files in your local node_modules directory.

@szszoke Yes, that was how I initially tested it. I also published a snapshot version of this branch: 0.0.0-fix-watch-mode-20240429115131.