Enhance folium-based mapping functions with styles, legends, and options

[srappel]

Expand create_map() in mapping.py with the following enhancements:

• Accept custom style function or color ramps
• Add layer toggling support for multiple institutions, scale ranges, or availability
• Add legend to map with scale and availability meaning
• Optional: add base layer selector (satellite, topo, etc.)
• Ensure output map is responsive and printable

Expose key style and behavior options via CLI.