Whether to render a secondary (right-side) y-axis. Default: false.
<insightdock/cartesian_chart.h>
virtual
bool
has_secondary_y_axis() const;
Override alongside compute_y2_min / compute_y2_max to enable a dual-axis layout (e.g. ComboChart assigning some series to the right axis). When true, PlotContext::y_scale2 is populated and the right margin is widened to fit its tick labels.