Fix Font.custom(_:size:relativeTo:) sizing on Android

[gurmeherchawla]

Summary

Font.custom(_:size:relativeTo:) was computing the Android font size incorrectly. The previous implementation added the base text style's system font size on top of the caller-supplied size:

let systemFont = system(textStyle)
let absoluteSize = systemFont.fontImpl().fontSize.value + size
androidx.compose.ui.text.TextStyle(fontSize: absoluteSize.sp)

This produced fonts that were too large (e.g. a .caption-relative custom font of 14pt would actually render at ~26sp), and the relativeTo style was being used as an additive offset rather than just a scaling reference.

Fix

Use size directly in sp units and drop the additive offset:

androidx.compose.ui.text.TextStyle(fontSize: size.sp)

size is the absolute point size at the default Dynamic Type level per the SwiftUI docs. Using sp ensures it scales proportionally with Android's font size accessibility setting — the closest equivalent to iOS Dynamic Type scaling.

This also aligns the behavior of Font.custom(_:size:relativeTo:) with the already-correct Font.custom(_:size:) implementation.

Testing

Personally tested on a real Android device with multiple Dynamic Type levels. Custom fonts now render at the expected size and scale correctly with accessibility font size changes.

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Fix authored with assistance from Claude Code (Anthropic). The fix and behavior have been personally reviewed and tested by the contributor.