feat(ios): honor textDecorationStyle on Text decorations

[quantizor]

Summary:

textDecorationStyle is declared on TextStyleIOS in the public types but wavy is silently dropped: Fabric's C++ enum doesn't include Wavy, and UIKit's NSUnderlineStyle has no native wavy pattern bit. Separately, dotted and dashed map to NSUnderlineStylePatternDot / NSUnderlineStylePatternDash which don't match browser geometry on iOS.

This PR adds TextDecorationStyle::Wavy to the shared Fabric primitives / conversions (also unblocks the same value on Android, see companion PR #56768) and renders wavy / dotted / dashed decorations with custom Core Graphics paths.

Implementation:

• Wavy ranges are tagged with a custom RCTCustomDecorationAttributeName (storing the line kinds, stroke color, and style key) in RCTAttributedTextUtils.mm and painted by RCTTextLayoutManager.mm after drawGlyphsForGlyphRange:. Wavy uses an adaptation of WebKit's formula from Source/WebCore/style/InlineTextBoxStyle.cpp (controlPointDistance = thickness * 1.5 + 0.5, one cubic Bezier per wavelength, control points at the midpoint above and below the y-axis). At iOS point sizes the literal Blink amplitude renders as a very pronounced wave because Core Graphics paints in points (not device pixels), so the constants are dialed back to read as a clear-but-subtle browser-style wave at typical text sizes.
• Dotted uses a custom CG path with a zero-length dash + round line caps, producing actual circular dots at 2 * thickness spacing.
• Dashed uses a custom CG path with [2 * thickness, thickness] intervals — short rectangular dashes with a tight gap, closer to Safari's geometry than UIKit's default.
• Solid and double continue to use UIKit's native NSUnderlineStyle pattern bits, so this PR does not touch the long-standing iOS Arial+bold solid-underline rendering bug tracked in [iOS] rendering Arial, underline and bold text produce bad underlining in specific case fontSize configuration #53935.
• The wavy drawing loop iterates while x < x2 so the final cycle continues through the last character (including trailing punctuation that would otherwise be visually uncovered when the run width is not an integer multiple of the wavelength).

Companion PRs (independent, also targeting main):

• fix(android): honor textDecorationColor on Text decorations #56767 — fix(android): textDecorationColor on underlines + strikethroughs. Resolves [Android] Issue with textDecoration #4579 (2015).
• feat(android): honor textDecorationStyle on Text decorations #56768 — feat(android): textDecorationStyle solid/double/dotted/dashed/wavy. Shares the TextDecorationStyle::Wavy enum addition; whichever lands first leaves the other with a trivial conflict to resolve.

Changelog:

[IOS] [ADDED] - textDecorationStyle: 'wavy' for <Text> (custom CoreGraphics path)
[IOS] [CHANGED] - textDecorationStyle: 'dotted' and 'dashed' for <Text> render with custom CoreGraphics paths instead of UIKit pattern bits, matching browser geometry more closely

Test Plan:

Side-by-side comparison on iPhone 17 sim (iOS 26.4) of a <Text> with textDecorationLine="underline" and textDecorationStyle cycling through solid / double / dotted / dashed / wavy, verified against Safari rendering of the same CSS. Trailing periods now fall under the wavy stroke. Verified with textDecorationColor set distinct from the foreground color.

<Text style={{
  color: 'black',
  textDecorationLine: 'underline',
  textDecorationStyle: 'wavy',
  textDecorationColor: '#ff00aa',
}}>
  Hello
</Text>

[meta-codesync]

@CalixTang has imported this pull request. If you are a Meta employee, you can view this in D104680636.

[github-actions]

Warning

JavaScript API change detected

This PR commits an update to ReactNativeApi.d.ts, indicating a change to React Native's public JavaScript API.

• Please include a clear changelog message.
• This change will be subject to additional review.

This change was flagged as: POTENTIALLY_BREAKING