const FRAME_HALF_STROKE: f32 = _; // 0.5f32Expand description
Half the block/port outline stroke width: a pin stub’s block-side endpoint
sits this far outside the bbox edge so it butts against the outline’s outer
face. The outline is centered on the edge (StrokeKind::Middle), so its
outer surface lies half a stroke-width out; stopping the stub there makes a
clean butt-joint instead of letting it run across the outline.