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/datasource_config.py

@@ -307,3 +307,40 @@ async def test_new_config(
             "error": "Connection failed",
             "message": str(e),
         }
+
+
+@router.get("/configs/all")
+async def list_all_datasources(
+    current_user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """List all data sources: YAML defaults + DB overrides"""
+    from app.core.data_sources import COLLECTOR_URL_KEYS, get_data_sources_config
+
+    config = get_data_sources_config()
+
+    db_query = await db.execute(select(DataSourceConfig))
+    db_configs = {c.name: c for c in db_query.scalars().all()}
+
+    result = []
+    for name, yaml_key in COLLECTOR_URL_KEYS.items():
+        yaml_url = config.get_yaml_url(name)
+        db_config = db_configs.get(name)
+
+        result.append(
+            {
+                "name": name,
+                "default_url": yaml_url,
+                "endpoint": db_config.endpoint if db_config else yaml_url,
+                "is_overridden": db_config is not None and db_config.endpoint != yaml_url
+                if yaml_url
+                else db_config is not None,
+                "is_active": db_config.is_active if db_config else True,
+                "source_type": db_config.source_type if db_config else "http",
+                "description": db_config.description
+                if db_config
+                else f"Data source from YAML: {yaml_key}",
+            }
+        )
+
+    return {"total": len(result), "data": result}