Collapse stop groups by default on collection screen

Drivers see a flat list of stops (suppliers / area clusters / POs)
on first load and tap one to drill into its items. Previously every
group auto-expanded on load, which buried the day at a glance under
every item row.

- Remove the three setExpanded*(allIds) auto-expand calls in loadItems
- Empty Set() defaults keep state stable across refreshes and tab switches
- expandAll() toolbar action still available for bulk-open
- SupplierGroup / AreaGroup already render the collapsed preview line
  (first 3 items +N more) so the stop's contents stay visible without
  expanding

app/page.tsx

@@ -146,23 +146,15 @@ const loadItems = useCallback(async (showLoading = true) => {
       setItems(data);
       setFilteredItems(data);
       setCached(statusFilter, data);
-      const allSupplierIds = new Set<string>();
-      data.forEach(i => {
-        if (i.expand?.supplier?.id) allSupplierIds.add(i.expand.supplier.id);
-      });
-      setExpandedSuppliers(allSupplierIds);
-      const allAreaIds = new Set<string>();
-      const clusters = clusterByProximity(data, 2);
-      clusters.forEach(c => allAreaIds.add(c.id));
-      setExpandedAreas(allAreaIds);
-      // Auto-expand every PO sub-group on first load — drivers want to
-      // see all of a PO's items at once. Per-PO collapse is opt-in.
-      const allPoIds = new Set<string>();
-      data.forEach(i => {
-        const po = i.expand?.purchase_order;
-        allPoIds.add(po?.id || '__no_po__');
-      });
-      setExpandedPOs(allPoIds);
+      // Default to ALL groups collapsed. Drivers see a flat list of
+      // stops (suppliers / area clusters / POs) on first load and tap
+      // one to drill into its items — matches the "open the app,
+      // see your day" mental model. The "Show all" toolbar action
+      // (`expandAll`) is still available for the rare case where a
+      // driver wants everything expanded at once.
+      setExpandedSuppliers(new Set());
+      setExpandedAreas(new Set());
+      setExpandedPOs(new Set());
     } catch (err) {
       console.error('Failed to load collections:', err);
       setError('Failed to load collections. Pull down to retry.');