add visualizations for old stats #51

[a-wyrm]

Hey! I've always loved this project and wanted to give a shot at adding a way to visualize older statistics (issue #51). Below are the things that I've changed:

ice_dentention_scraper.py

def extract_facilities_data( filepath: str, source_date: str | None = None ) -> dict | None:

This can now extract data from xlsx files from years other than 2026. It also reformats the returned dictionary object to work better with the map rendering.

render_facilities_map.py

create_timeline_dict(timeline_data: dict) -> dict:

This builds the dictionary object, which now holds both current and prior ICE data.

map.html

The map page now has a slider and defaults to the current year! When users slide it, the page will automatically render new leaflet.js markers using the dictionary object built in the above functions.

Other changes:

• All of the xlsx files have their own dictionary in the data folder now. This was to just keep the data folder more organized.

I'm working on collecting the archived data from archive.org, and will make another pull request once I've gotten all of the historic data.