Create an export job to generate crag-only geojson

[vnugent]

Use case

As a consumer of OB data, when building interactive maps, I want to have a vector map layer with all the crags included (as points), similar to how rivers, roads, buildings, etc are parts of a layer. This layer can be used by openbeta.io or anyone using mapbox-gl or maplibre.

• [x] create crag exporter job
• [x] calculate area polygons
• [x] manually import files to MB studio

[vnugent]

the cronjob now exports crag.geojson.gz to https://github.com/OpenBeta/openbeta-export I'll set it to run daily. We'll need a separate task to upload it to Mapbox studio.

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