Fix Leaflet attribution positioning with bottom navbar

Add margin adjustments to .leaflet-bottom.leaflet-left to ensure the
attribution doesn't overlap with the fixed bottom navbar and has proper
spacing from the left edge of the viewport.

Author: claude

css/catchment.css

@@ -279,6 +279,12 @@ body {
     margin-top: 60px;
 }
 
+/* Ensure Leaflet attribution doesn't overlap with bottom navbar */
+.leaflet-bottom.leaflet-left {
+    margin-bottom: 60px;
+    margin-left: 10px;
+}
+
 /* Better popup styling */
 .leaflet-popup-content {
     margin: 13px 19px;