feat(flyer-import): add bundle support and new product fields

- Add bundle support with isBundle, bundleWeight, and bundleItems fields
- Add brand, weight, and comparisonUnit fields to FlyerItem model
- Update AI flyer parser to extract bundle information
- Add sanitization for bundle items in FlyerNormalizerService
- Update DTOs and interfaces to include new fields
- Add migration for new database fields
- Update tests to cover bundle item handling

backend/src/flyer-import/dto/flyer-import.response.ts

@@ -4,13 +4,18 @@ export type FlyerImportItem = {
   flyerItemId: number | null;
   rawName: string;
   normalizedName: string;
+  brand: string | null;
   category: string | null;
   categoryId: number | null;
-  price: number | null;
-  priceUnit: string | null;
-  comparisonPrice: number | null;
-  comparisonUnit: string | null;
-  offerText: string | null;
+  price: number | null;
+  priceUnit: string | null;
+  comparisonPrice: number | null;
+  comparisonUnit: string | null;
+  weight: string | null;
+  bundleWeight: string | null;
+  isBundle: boolean;
+  bundleItems: string[];
+  offerText: string | null;
   isOffer: boolean;
   offerLimitText: string | null;
   parseConfidence: number;