Revised checkbox-tree functions and related

src/main.js

@@ -139,6 +139,7 @@ async function initializeVisibilityTree() {
     initiallySelected: true,
     storageKey: "a-plot-of-plants:visibility:v1",
     manifest,
+    stateEncoding: "tiered",
     onSelectionChange: ({ selectedNodes }) => {
       selectedFeatureIndexes = getSelectedFeatureIndexes(selectedNodes);
       renderYardForDate(selectedTimelineDate);