feat: enhance ProductPickerField to use rawName for initial query in receipt import

flutter/lib/core/ui/product_picker_field.dart

@@ -91,6 +91,7 @@ class ProductPickerField extends StatelessWidget {
   }
 
   Future<void> _openPicker(BuildContext context) async {
+    // Skapa controller utanför showSheet för att undvika reset vid rebuild
     final result = await ProductPickerField.showSheet(
       context,
       products: products,
@@ -121,6 +122,8 @@ class ProductPickerField extends StatelessWidget {
       isScrollControlled: true,
       useSafeArea: true,
       builder: (sheetContext) {
+        // Skapa controller EN gång per öppnad ark — inte inuti StatefulBuilder
+        final controller = TextEditingController(text: initialQuery ?? '');
         var query = initialQuery ?? '';
 
         return StatefulBuilder(
@@ -155,7 +158,7 @@ class ProductPickerField extends StatelessWidget {
                     padding: const EdgeInsets.fromLTRB(16, 0, 16, 8),
                     child: TextField(
                       autofocus: true,
-                      controller: TextEditingController(text: initialQuery ?? ''),
+                      controller: controller,
                       decoration: const InputDecoration(
                         hintText: 'Sök produkt...',
                         prefixIcon: Icon(Icons.search),