fix: keep wrapping item labels in line with their fields (#2048)

[clinnygee]

Fixes #2048.

Problem

In the "Absolute cardiovascular disease risk calculation" section of the Aboriginal and Torres Strait Islander Health Check, the question "Do you have access to the Aus CVD Risk-i application from your clinical system?" rendered well below its Yes/No radios rather than beside them.

This was not specific to that question — any item label long enough to wrap onto a second line was affected, for plain text, rendering-xhtml and rendering-markdown alike.

Causes

Two independent issues, both in ItemLabel:

1. Inline-flex baseline. The label text sits in a display: inline-flex box. An inline-flex box takes its baseline from its first flex item — here the usually-empty prefix span. Once the text wrapped, that baseline sat ~15px below the surrounding line box's baseline, pushing the whole label down. The box now aligns to the top of its line box.

2. XHTML paragraph margins. Labels supplied as rendering-xhtml are wrapped in a <p>, whose margin-block-start added a further 14px. Question labels now trim their outer paragraph margins. Display items keep theirs, since they are standalone blocks of prose rather than a single run of label text.

Group headings were never affected — their Typography is already a flex container, which blockifies the inner box and removes it from the line box entirely. Grid groups are also unaffected, since their table cells centre vertically; GridRow/GridTable are left alone.

Result

Measured from the top of the row to the first line of label text:

Label	Before	After
Plain text	25px	10px
rendering-xhtml	25px	10px
String item	25px	10px

10px is the offset a single-line label already had (ItemLabel's 4px nudge plus the line's half-leading), so wrapping labels now sit exactly where non-wrapping ones do.

Verified by rendering the real assembled 715 questionnaire's CVD section: the question now lines up with its radios, matching the plain-text question directly above it.

Testing

• New WrappingItemLabels story under SDC/9.1.1 Rendering > Text Appearance, covering plain, xhtml and string wrapping labels. Its play function asserts the first line of label text starts at the top of its row; it passes with the fix and fails (25px > 12px threshold) without it.
• Renderer build (tsc) and root npm run lint pass with no errors.
• Renderer Jest suite: 92/92 suites, 2190 tests pass.
• Storybook test-runner passes for the affected suite.

🤖 Generated with Claude Code