feat: enhance ProductPickerField and ParsedReceiptItem to support category filtering in receipt import

flutter/lib/features/import/domain/parsed_receipt_item.dart

@@ -15,6 +15,7 @@ class ParsedReceiptItem {
   // AI-kategorisuggestion (premium)
   final String? categorySuggestionName;
   final String? categorySuggestionPath;
+  final int? categorySuggestionId;
 
   ParsedReceiptItem({
     required this.rawName,
@@ -29,6 +30,7 @@ class ParsedReceiptItem {
     this.suggestedProductName,
     this.categorySuggestionName,
     this.categorySuggestionPath,
+    this.categorySuggestionId,
   });
 
   factory ParsedReceiptItem.fromJson(Map<String, dynamic> json) {
@@ -46,6 +48,7 @@ class ParsedReceiptItem {
       suggestedProductName: json['suggestedProductName'] as String?,
       categorySuggestionName: cat?['categoryName'] as String?,
       categorySuggestionPath: cat?['path'] as String?,
+      categorySuggestionId: (cat?['categoryId'] as num?)?.toInt(),
     );
   }
 }