refactor(Stack): vanilla extract

[matthprost]

Summary

Type

• Refactor

Summarise concisely:

What is expected?

Refactor stack using vanilla extract

[changeset-bot]

🦋 Changeset detected

Latest commit: 7a3204f

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

This PR includes changesets to release 4 packages

Name	Type
@ultraviolet/ui	Minor
@ultraviolet/form	Major
@ultraviolet/nextjs	Major
@ultraviolet/plus	Major

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.21%. Comparing base (ae2a8ee) to head (7a3204f).
⚠️ Report is 2 commits behind head on beta.

Additional details and impacted files

@@            Coverage Diff             @@
##             beta    #5492      +/-   ##
==========================================
+ Coverage   92.05%   92.21%   +0.16%     
==========================================
  Files         251      257       +6     
  Lines        7964     7930      -34     
  Branches     3405     3376      -29     
==========================================
- Hits         7331     7313      -18     
+ Misses        633      617      -16     

Files with missing lines	Coverage Δ
packages/ui/src/components/Stack/index.tsx	82.14% <ø> (+18.98%)	⬆️
packages/ui/src/components/Stack/styles.css.ts	100.00% <ø> (ø)
packages/ui/src/components/Stack/variables.css.ts	100.00% <ø> (ø)

... and 4 files with indirect coverage changes

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