fix(sidebar): use sidebar theme color for sticky database rows

apps/desktop/src/components/sidebar/ConnectionTree.vue

@@ -2806,7 +2806,7 @@ defineExpose({ focusSearch, createNewGroup, collapseAllTreeNodes, locateTabInSid
 
 <style scoped>
 .sticky-database-header {
-  background-color: var(--background);
+  background-color: var(--sidebar);
 }
 
 .connection-tree-scroller {

apps/desktop/src/components/sidebar/TreeItem.vue

@@ -1773,7 +1773,7 @@ function onKeydown(event: KeyboardEvent) {
   position: sticky;
   top: 0;
   z-index: 2;
-  background-color: var(--background);
+  background-color: var(--sidebar);
 }
 
 .tree-item-connection-tint:hover::before {