feat:css-varables-toggle

[Austin1serb]

Summary

Added support to flip css varables on the body or target element, by passing in a cssVar flag into either hook, for example to add blur:

	const [blur, setBlur] = useScopedUI<'0px' | '4px'>('blur', '0px', cssVar);
```, now that will set the css varable on that elemnet and toggle it without rerenders.
<!-- Briefly describe the purpose of this PR and what it changes. If fixing an issue, reference it with "Closes #123". -->

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## Type of Change

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- [ ] 🐛 Bug fix
- [X] ✨ New feature
- [ ] 🛠 Refactor
- [ ] 🧪 Test improvement
- [ ] 📝 Docs update
- [ ] ⚙️ CI/tooling

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## Checklist

- [X] All tests pass (`pnpm test`)
- [X] Linting and formatting pass (`pnpm lint && pnpm format`)
- [X] PR title follows semantic commit format (`feat:`, `fix:`, etc.)
- [ ] Changes are documented (README, JSDoc, or comments if needed)
- [X] Ready for review — not a draft

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## Notes for Reviewer

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Name	Status	Preview	Comments	Updated (UTC)
react-zero-ui	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Aug 2, 2025 0:39am

[Austin1serb]

good to go