Function render_colr_glyph_from_atlas 

fn render_colr_glyph_from_atlas(
    renderer: &mut impl GlyphRenderer,
    atlas_slot: AtlasSlot,
    transform: Affine,
    area: Rect,
)

Render a COLR glyph from the atlas cache.

This version accepts a pre-calculated fractional area to preserve sub-pixel accuracy during rendering, avoiding scaling artifacts.