[eslint-plugin] Add place-content/place-items/place-self shorthand expansion to stylex-valid-shorthands

[abhakat]

What changed / motivation ?

Expand placeContent, placeItems, and placeSelf two-value shorthands into align/justify longhands.

• placeContent: 'center space-between' → alignContent: 'center' + justifyContent: 'space-between'
• placeItems: 'center start' → alignItems: 'center' + justifyItems: 'start'
• placeSelf: 'center start' → alignSelf: 'center' + justifySelf: 'start'
• Single values pass through unchanged

Linked PR/Issues

Follow-up to #1553, #1552

Additional Context

Tests covering: single-value passthrough, 2-value align/justify expansion, !important propagation.

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 6:20pm

[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.v2ISvo42Qe /tmp/tmp.QYjspLwRy6

Results	Base	Patch	Ratio
babel-plugin: stylex.create
· basic create	556	535	0.96	-
· complex create	67	67	1.00
babel-plugin: stylex.createTheme
· basic themes	443	440	0.99	-
· 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.l8DuwVOoMj /tmp/tmp.1GEmJeGT3A

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 0.09s.
Done in 0.36s.