feat: add aggregated ES(t) plotting and verification

- Modified plot_ES_results to return fig, ax, all_x_coords for external plotting
- Added manual plotting of aggregated ES(t) curves in main function
- Both microscopic and aggregated curves are plotted on the same graph
- Aggregated curves use dashed lines with square markers for distinction
- All verification checks pass with floating-point precision differences (1.39e-17)

Author: Dayuxiaoshui