chore: generate CSS hash using the filename

[Ocean-OS]

Closes #16636, alternative to #16697.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 8ee268f

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

This PR includes changesets to release 1 package

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svelte	Patch

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-svelte-16740-svelte.vercel.app/

[github-actions]

Playground

pnpm add https://pkg.pr.new/svelte@16740

[Rich-Harris]

Ah. This fails because filename is often absolute, meaning it differs based on where it runs. We don't have a good way to enforce project-relative filenames, and making builds non-deterministic seems bad. I'm now therefore of the opinion that we shouldn't make this change.

[Ocean-OS]

What if we use the closest package.json to determine the project's root directory, and then replace any backslashes with slashes (so windows doesn't differ from everything else)?

[Rich-Harris]

Oh actually, we have rootDir available... maybe we can just use that. Taking a run at it