feat: add data sources config system and Earth API integration

- Add data_sources.yaml for configurable data source URLs
- Add data_sources.py to load config with database override support
- Add arcgis_landing_points and arcgis_cable_landing_relation collectors
- Change visualization API to query arcgis_landing_points
- Add /api/v1/datasources/configs/all endpoint
- Update Earth to fetch from API instead of static files
- Fix scheduler collector ID mappings

frontend/public/earth/js/main.js

@@ -171,7 +171,6 @@ function onMouseMove(event, camera) {
         c.material.opacity = 1;
       });
       hoveredCable = cable;
-      hoveredCable = cable;
     }
     
     const userData = cable.userData;