add loading

lib/features/products/presentation/pages/products_page.dart

@@ -28,6 +28,7 @@ class _ProductsPageState extends ConsumerState<ProductsPage>
     with SingleTickerProviderStateMixin {
   late TabController _tabController;
   String _currentOperationType = 'import';
+  bool _isTabSwitching = false;
 
   @override
   void initState() {
@@ -52,6 +53,7 @@ class _ProductsPageState extends ConsumerState<ProductsPage>
       if (_currentOperationType != newOperationType) {
         setState(() {
           _currentOperationType = newOperationType;
+          _isTabSwitching = true; // Mark that tab is switching
         });
 
         // Load products for new operation type
@@ -230,6 +232,18 @@ class _ProductsPageState extends ConsumerState<ProductsPage>
     final isLoading = productsState.isLoading;
     final error = productsState.error;
 
+    // Listen to products state changes to clear tab switching flag
+    ref.listen(productsProvider, (previous, next) {
+      // Clear tab switching flag when loading completes
+      if (previous?.isLoading == true && next.isLoading == false) {
+        if (_isTabSwitching) {
+          setState(() {
+            _isTabSwitching = false;
+          });
+        }
+      }
+    });
+
     return Scaffold(
       appBar: AppBar(
         title: Column(
@@ -361,8 +375,10 @@ class _ProductsPageState extends ConsumerState<ProductsPage>
     required List products,
     required ThemeData theme,
   }) {
-    // Loading state
-    if (isLoading && products.isEmpty) {
+    // Loading state - show when:
+    // 1. Loading and no products, OR
+    // 2. Tab is switching (loading new products for different operation type)
+    if (isLoading && (products.isEmpty || _isTabSwitching)) {
       return const Center(
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,