Fix variables table hiding logic - now correctly hides when get_variables returns no results on first page, regardless of search query; also fixed 'No results' message flashing during search to only show after completion.

Author: John Rogers

.cursor-updates

@@ -69,4 +69,5 @@
 - Changed filterMode and sortingMode to "client" (pagination remains "server") - filtering and sorting now happen client-side on fetched data, rowCount from API response (num_hits) is passed to DataGrid for proper pagination display
 - Updated rowCount logic: on first page with filter, use results.length if < pageSize (exact) or pageSize if full page (minimum); on first page without filter, use num_hits (unfiltered total). When no query, only send ancestor_uuid, offset, and num_results to API (table handles offset/limit). Green bar variable count captures num_hits from first DataGrid request (num_hits is always unfiltered total regardless of query). Simplified refs - removed complex tracking, just reset request key when study changes to prevent duplicate calls. QuickFilter only initialized with mainSearchQuery if variablesWhichMatched exists and has items, otherwise set to empty
 - Removed duplicate request prevention that was blocking legitimate DataGrid requests
-- Fixed 'No results' message flashing during search - now only shows after search actually completes (loading goes from true to false), preventing false "0 results" display while search is in progress
+- Fixed 'No results' message flashing during search - now only shows after search actually completes (loading goes from true to false), preventing false "0 results" display while search is in progress
+- Fixed variables table hiding logic - now correctly hides when get_variables returns no results on first page, regardless of whether there's a search query