fix(transform): deduplicate CSS rules from resolveStyleRulesForSlots

[layershifter]

Summary

• dedupeCSSRules() was being called on the previously accumulated cssRulesByBucket instead of the freshly resolved resolvedCSSRules. This meant duplicates within each makeStyles call were never removed from the intermediate result.
• The deduplicated result (uniqueCSSRules) was only used for metadata — the raw un-deduplicated resolvedCSSRules was appended to the output bucket.

This does not affect the final generated CSS (the webpack plugin deduplicates when collecting CSS across modules), but it does cause the cssRulesByBucket returned by transformSync() to contain duplicate entries — LTR/RTL pairs and cross-slot duplicates.

Fix

- const uniqueCSSRules = dedupeCSSRules(cssRulesByBucket);
+ const uniqueCSSRules = dedupeCSSRules(resolvedCSSRules);
  ...
- cssRulesByBucket = concatCSSRulesByBucket(cssRulesByBucket, resolvedCSSRules);
+ cssRulesByBucket = concatCSSRulesByBucket(cssRulesByBucket, uniqueCSSRules);

This matches how @griffel/babel-preset handles deduplication (line 341 of transformPlugin.ts).

Test plan

• All 79 transform tests pass (3 snapshots updated to remove duplicate entries)

[github-actions]

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