Function draw_clock_edge_marks 

pub(crate) fn draw_clock_edge_marks(
    clock_edges: &ClockHighlightData,
    ctx: &mut DrawingContext<'_>,
    config: &SurferConfig,
)

Draws clock highlight marks for the currently selected highlight mode.

Line mode draws vertical lines (or interleaved dashes for coincident edges), while Cycle mode paints alternating cycle spans for each active clock.