perf(collections): coalesce duplicate refresh triggers during in-flight loads

lib/screens/collections_screen.dart

@@ -21,6 +21,8 @@ class CollectionsScreenState extends State<CollectionsScreen>
   with WidgetsBindingObserver {
   List<Collection> _collections = [];
   bool _isLoading = true;
+  bool _isLoadInFlight = false;
+  bool _reloadQueued = false;
   String? _error;
   String? _activeCollectionId;
   DateTime _lastLoadedAt = DateTime.fromMillisecondsSinceEpoch(0);
@@ -61,11 +63,20 @@ class CollectionsScreenState extends State<CollectionsScreen>
     }
   }
 
-  Future<void> _load() async {
+  Future<void> _load({bool showLoading = true}) async {
-    setState(() {
+    if (_isLoadInFlight) {
-      _isLoading = true;
+      _reloadQueued = true;
-      _error = null;
+      return;
-    });
+    }
+
+    _isLoadInFlight = true;
+
+    if (showLoading) {
+      setState(() {
+        _isLoading = true;
+        _error = null;
+      });
+    }
 
     try {
       var list = await CollectionService.getMyCollections();
@@ -119,6 +130,12 @@ class CollectionsScreenState extends State<CollectionsScreen>
         _isLoading = false;
       });
       logError('collections.load', e);
+    } finally {
+      _isLoadInFlight = false;
+      if (_reloadQueued) {
+        _reloadQueued = false;
+        Future<void>.microtask(() => _load(showLoading: false));
+      }
     }
   }