Add Ruggieri & Antonellis capabilities

[CommonClimate]

• translate their code to Python
• incorporate into ammonyte/utils/RuggieriAntonellis.py
• attach methods to the Ammonyte series class
• create functionalities to plot and export results (a new results class may or may not be necessary)
• ask Claude to create detailed docstrings in the Pyleoclim style (using the Jupyter-execute decorator), using the NGRIP example
• create a Jupyter notebook (under /notebooks) that reproduces the results of their paper