feat(layout): add wrap support for row/column stacks

[RtlZeroMemory]

Summary

• add wrap?: boolean to RowProps and ColumnProps (default remains false)
• implement wrap-aware measure/layout for row and column stacks in stack.ts
• apply justify/align per wrapped line and apply gap both within lines and between lines
• run flex distribution per line in wrap mode (not globally)
• keep non-wrap behavior unchanged

Tests

• add packages/core/src/layout/__tests__/layout.wrap.test.ts with 28 deterministic wrap cases
• run full validation:
  • npm run build
  • npm run typecheck
  • node scripts/run-tests.mjs (2486 passing)

Docs

• update docs/guide/layout.md with a stack wrap section including percentage-size semantics in wrap mode

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Derive wrapped line cross-size before stretching children

With wrap: true and align: "stretch", this line sets each child’s cross size to the full container cross size (ch), so every wrapped line gets line.cross == ch; the subsequent lineY += line.cross + gap then pushes later lines by an entire container height instead of by that line’s intrinsic cross size. This produces visibly incorrect multi-line placement (and the same pattern exists in the column path), so line cross-size should be computed from measured children first and stretch should only be applied when laying out each child.

Useful? React with 👍 / 👎.

[RtlZeroMemory]

Fixed in d81b073.

Changes:

• wrapped line cross-size is now always derived from measured child intrinsic cross-size in both measurement and layout planning paths
• align: "stretch" now only forces child cross-size during per-line layout (it no longer inflates line.cross to full container cross-size)
• added regression tests:
  • row wrap align=stretch uses per-line intrinsic cross size
  • column wrap align=stretch uses per-line intrinsic cross size

Validation run: npm run lint, npm run build, npm run typecheck, node scripts/run-tests.mjs (all passing).