feat: implement two-step category and product picker for enhanced selection

flutter/lib/features/import/presentation/receipt_import_tab.dart

@@ -4,8 +4,11 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../../../core/api/api_error_mapper.dart';
 import '../../../core/api/api_paths.dart';
 import '../../../core/api/api_providers.dart';
+import '../../../core/ui/category_then_product_picker.dart';
 import '../../../core/ui/product_picker_field.dart';
 import '../../../core/utils/global_error_handler.dart';
+import '../../admin/data/admin_repository.dart';
+import '../../admin/domain/admin_category_node.dart';
 import '../../auth/data/auth_providers.dart';
 import '../../inventory/data/inventory_providers.dart';
 import '../../inventory/domain/inventory_item.dart';
@@ -40,11 +43,13 @@ class _EditDialog extends StatefulWidget {
   final ParsedReceiptItem item;
   final _ItemEdit current;
   final List<ProductOption> products;
+  final List<AdminCategoryNode> categoryTree;
 
   const _EditDialog({
     required this.item,
     required this.current,
     required this.products,
+    required this.categoryTree,
   });
 
   @override
@@ -88,6 +93,26 @@ class _EditDialogState extends State<_EditDialog> {
     // Visa hela sökvägen om det finns, annars bara kategorinamnet
     final aiLabel = aiPath != null && aiPath.isNotEmpty ? aiPath : aiCategory;
 
+    // Hjälpfunktion: välj produkt via tvåstegs-picker (kategori → produkt)
+    Future<void> openCategoryPicker({int? preselectedCategoryId}) async {
+      final id = await CategoryThenProductPicker.show(
+        context,
+        categoryTree: widget.categoryTree,
+        products: widget.products,
+        currentProductId: _productId,
+        preselectedCategoryId: preselectedCategoryId,
+      );
+      if (id != null && mounted) {
+        setState(() {
+          _productId = id;
+          _productName = widget.products
+              .cast<ProductOption?>()
+              .firstWhere((p) => p?.id == id, orElse: () => null)
+              ?.name;
+        });
+      }
+    }
+
     // Hjälpfunktion: acceptera AI-förslaget
     void acceptAiSuggestion() {
       final sugId = item.suggestedProductId;
@@ -97,28 +122,9 @@ class _EditDialogState extends State<_EditDialog> {
           _productId = sugId;
           _productName = item.suggestedProductName;
         });
-      } else if (aiCategory != null) {
-        // Öppna pickern filtrerad på AI-föreslagen kategori (categoryId).
-        // Visar bara produkter i den kategorin (eller rawName-sökning om kategorin är tom).
-        final catId = item.categorySuggestionId;
-        ProductPickerField.showSheet(
-          context,
-          products: widget.products,
-          value: _productId,
-          label: 'Produkt',
-          initialQuery: item.rawName,
-          categoryFilter: catId != null ? {catId} : null,
-        ).then((id) {
-          if (id != null && mounted) {
-            setState(() {
-              _productId = id;
-              _productName = widget.products
-                  .cast<ProductOption?>()
-                  .firstWhere((p) => p?.id == id, orElse: () => null)
-                  ?.name;
-            });
-          }
-        });
+      } else {
+        // Öppna kategori → produkt med AI-föreslagen kategori förvald
+        openCategoryPicker(preselectedCategoryId: item.categorySuggestionId);
       }
     }
 
@@ -141,14 +147,14 @@ class _EditDialogState extends State<_EditDialog> {
                     visualDensity: VisualDensity.compact,
                     tooltip: item.suggestedProductId != null
                         ? 'Välj "${item.suggestedProductName}" automatiskt'
-                        : 'Sök produkter i kategorin "$aiCategory"',
+                        : 'Bläddra produkter i kategorin "$aiCategory"',
                     onPressed: acceptAiSuggestion,
                   ),
                 ],
               ),
               const SizedBox(height: 8),
             ],
-    // Destination
+            // Destination
             SegmentedButton<_Destination>(
               segments: const [
                 ButtonSegment(
@@ -167,21 +173,40 @@ class _EditDialogState extends State<_EditDialog> {
               style: const ButtonStyle(visualDensity: VisualDensity.compact),
             ),
             const SizedBox(height: 12),
-            ProductPickerField(
-              products: widget.products,
-              value: _productId,
-              label: 'Produkt',
-              onChanged: (id) {
-                setState(() {
-                  _productId = id;
-                  _productName = id == null
-                      ? null
-                      : widget.products
-                          .cast<ProductOption?>()
-                          .firstWhere((p) => p?.id == id, orElse: () => null)
-                          ?.name;
-                });
-              },
+            // Produktval: sök direkt eller välj via kategoriträd
+            Row(
+              children: [
+                Expanded(
+                  child: ProductPickerField(
+                    products: widget.products,
+                    value: _productId,
+                    label: 'Produkt',
+                    onChanged: (id) {
+                      setState(() {
+                        _productId = id;
+                        _productName = id == null
+                            ? null
+                            : widget.products
+                                .cast<ProductOption?>()
+                                .firstWhere((p) => p?.id == id, orElse: () => null)
+                                ?.name;
+                      });
+                    },
+                  ),
+                ),
+                const SizedBox(width: 8),
+                Tooltip(
+                  message: 'Välj via kategori',
+                  child: OutlinedButton(
+                    style: OutlinedButton.styleFrom(
+                      minimumSize: const Size(44, 56),
+                      padding: EdgeInsets.zero,
+                    ),
+                    onPressed: () => openCategoryPicker(),
+                    child: const Icon(Icons.account_tree_outlined, size: 20),
+                  ),
+                ),
+              ],
             ),
             const SizedBox(height: 12),
             if (_destination == _Destination.inventory) ...[
@@ -255,6 +280,9 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
   List<ProductOption> _products = [];
   bool _loadingProducts = false;
 
+  // Kategoriträdet för tvåstegs-picker
+  List<AdminCategoryNode> _categoryTree = [];
+
   // Befintligt inventarie: productId → InventoryItem (för sammanslagning)
   Map<int, InventoryItem> _inventoryByProduct = {};
 
@@ -272,7 +300,12 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
     try {
       final token = await ref.read(authStateProvider.future);
       final api = ref.read(apiClientProvider);
-      final data = await api.getJson(ProductApiPaths.list, token: token);
+      final adminRepo = ref.read(adminRepositoryProvider);
+      final results = await Future.wait([
+        api.getJson(ProductApiPaths.list, token: token),
+        adminRepo.listCategoryTree(),
+      ]);
+      final data = results[0];
       final list = data is List ? data : ((data as Map<String, dynamic>?)?['items'] as List? ?? []);
       if (mounted) {
         setState(() {
@@ -280,6 +313,7 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
               .cast<Map<String, dynamic>>()
               .map((e) => (id: e['id'] as int, name: e['name'] as String, categoryId: (e['categoryId'] as num?)?.toInt()))
               .toList();
+          _categoryTree = results[1] as List<AdminCategoryNode>;
           _loadingProducts = false;
         });
       }
@@ -379,7 +413,7 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
 
     final result = await showDialog<_ItemEdit>(
       context: context,
-      builder: (_) => _EditDialog(item: item, current: current, products: _products),
+      builder: (_) => _EditDialog(item: item, current: current, products: _products, categoryTree: _categoryTree),
     );
     if (result != null && mounted) {
       setState(() {