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

backend/app/api/v1/dashboard.py

@@ -14,6 +14,7 @@ from app.models.task import CollectionTask
 from app.core.security import get_current_user
 from app.core.cache import cache
 
+
 # Built-in collectors info (mirrored from datasources.py)
 COLLECTOR_INFO = {
     "top500": {