GSHorizontalTypesetter improvements: Implement Proper Paragraph Spacing

[IOOI-SqAR]

I asked the Kimi AI how to further improve GSHorizontalTypesetter. Here is what it came up with:

https://www.kimi.com/share/19d34cdb-8242-8fc9-8000-00001fd46e3b

Implement Proper Paragraph Spacing

The code mentions paragraph spacing but doesn't apply it:

// In layoutLineNewParagraph:, after completing a paragraph:
if (newParagraph) {
    CGFloat paragraphSpacing = [currentParagraphStyle paragraphSpacing];
    currentPoint.y += paragraphSpacing;  // Add space after paragraph
}