Display POIs and other contextual layers

Hi,

It would be useful to have a toggle to display sets of POIs. For example display all the schools or all the shops in the study area would be a good start for my use-cases.

Thanks

The issue requests a toggle to display POI layers like schools and shops on the map. Start by exploring the frontend map rendering code, likely in a directory like `map_gui` or `widgets`. Look for existing layer toggles and how geographic data (GeoJSON, etc.) is loaded and styled. Determine where POI data is sourced and how to add a new UI control to filter and display it. Check for any tests related to map layers.

Written by the indexing model from the issue text.