[eslint-plugin] Add inset shorthand expansion to stylex-valid-shorthands

[abhakat]

What changed / motivation ?

Expand inset, insetBlock, and insetInline shorthands into longhands.

• inset: '0 10px' → insetBlock: '0' + insetInline: '10px' (2-value logical)
• inset: '0 10px 20px' → top + right + bottom + left (3-4 value, physical per CSS spec)
• insetBlock: '0 10px' → insetBlockStart + insetBlockEnd
• insetInline: '0 10px' → insetInlineStart + insetInlineEnd
• Single values pass through unchanged

Linked PR/Issues

Follow-up to #1553, #1552

Additional Context

Tests covering: single-value passthrough, 2/3/4-value expansion, preferInline option,
insetBlock/insetInline axis expansion.

Pre-flight checklist

• I have read the contributing guidelines
  Contribution Guidelines
• Performed a self-review of my code

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
stylex	Skipped		Apr 6, 2026 6:18pm

[github-actions]

workflow: benchmarks/perf

Comparison of performance test results, measured in operations per second. Larger is better.
yarn workspace v1.22.22
yarn run v1.22.22
$ node ./compare.js /tmp/tmp.SM3xSSlGv0 /tmp/tmp.oT4G9unYYn

Results	Base	Patch	Ratio
babel-plugin: stylex.create
· basic create	544	547	1.01	+
· complex create	67	67	1.00
babel-plugin: stylex.createTheme
· basic themes	445	446	1.00	+
· complex themes	34	34	1.00
Done in 0.08s.
Done in 0.32s.

[github-actions]

workflow: benchmarks/size

Comparison of minified (terser) and compressed (brotli) size results, measured in bytes. Smaller is better.
yarn workspace v1.22.22
yarn run v1.22.22
$ node ./compare.js /tmp/tmp.napevQmVA2 /tmp/tmp.ZbxjipBJfJ

Results	Base	Patch	Ratio
@stylexjs/stylex/lib/cjs/stylex.js
· compressed	1,441	1,441	1.00
· minified	4,386	4,386	1.00
@stylexjs/stylex/lib/cjs/inject.js
· compressed	1,793	1,793	1.00
· minified	4,915	4,915	1.00
benchmarks/size/.build/bundle.js
· compressed	496,650	496,650	1.00
· minified	4,847,840	4,847,840	1.00
benchmarks/size/.build/stylex.css
· compressed	99,653	99,653	1.00
· minified	747,850	747,850	1.00
Done in 0.07s.
Done in 0.32s.