feat(flyer-import): add cheese variant splitting and normalization rules

- Add logic to split Swedish cheese variants (Präst, Herrgård, Grevé) into separate products
- Implement brand normalization for "Arla Ko" and category assignment to "Hårdost"
- Update flyer parser with detailed rules for bundle/group announcements
- Add unit tests for variant splitting and brand/category normalization
- Replace single-item return with flatMap for expanded product lists

backend/src/flyer-import/services/ai-flyer-parser.service.ts

@@ -182,12 +182,23 @@ Returnera objekt med exakt dessa fält:
 - unit: string | null (enhet for jamforpris, t.ex. kg/l/st)
 - offer: string[]
 
+Arbetssatt (viktigt):
+Steg A) Identifiera om texten ar en gruppannons med flera varianter + gemensamma attribut.
+Steg B) Returnera en post per faktisk produktvariant med arvd metadata.
+
 Regler:
 1) Vanlig produkt (ej bundle): isBundle=false, bundleWeight=null, bundleItems=[].
 2) Kombipaket/bundle: isBundle=true, name ska vara paketets huvudnamn, bundleWeight totalvikt.
 3) For bundle ska bundleItems innehalla de ingaende produkterna, t.ex. ["Chumlax 3x100g", "Alaska pollock 3x100g"].
 4) price ar priset for hela forpackningen. comparisonPrice ar jamforpris som tal ("83:17" -> 83.17).
 5) offer innehaller kampanjtext som "Max 10 kop/hushall".
+6) Om en rubrik/lista innehaller flera kommaseparerade namn och efterfoljande rad/rader innehaller gemensam brand, vikt, pris eller kampanjvillkor: expandera till separata objekt (en per namn) och arv all gemensam metadata.
+7) Tillämpa samma split-regel generellt for liknande tillbud (inte bara ost), nar listan tydligt representerar produktvarianter/smaker/sorter.
+8) Splitta INTE om listan snarare ar ingredienser, avdelningar, eller otydlig marknadsforing utan tydlig produktvariant.
+9) Specialregel ost: namn som PRAST/HERRGARD/GREVE ska normaliseras till Prastost/Herrgardsost/Greveost.
+10) Om texten innehaller "ARLA KO" ska brand vara exakt "Arla Ko".
+11) For ovan ostsorter ska category vara "Hardost".
+12) Returnera aldrig extra nycklar, text, markdown eller forklaringar utanfor JSON-arrayen.
 
 Exempel bundle utdata:
 [
@@ -223,6 +234,42 @@ Exempel enkel produkt utdata:
   }
 ]
 
+Exempel gruppannons med varianter (ska splittas):
+Input-idé: "PRAST, HERRGARD, GREVE" + "ARLA KO" + gemensam vikt/pris.
+Output-idé:
+[
+  {
+    "name": "Prastost",
+    "brand": "Arla Ko",
+    "category": "Hardost",
+    "isBundle": false,
+    "weight": "667g",
+    "bundleWeight": null,
+    "bundleItems": [],
+    "price": null,
+    "comparisonPrice": 79.90,
+    "unit": "kg",
+    "offer": ["Max 3 forp/hushall"]
+  },
+  {
+    "name": "Herrgardsost",
+    "brand": "Arla Ko",
+    "category": "Hardost",
+    "isBundle": false,
+    "weight": "667g",
+    "bundleWeight": null,
+    "bundleItems": [],
+    "price": null,
+    "comparisonPrice": 79.90,
+    "unit": "kg",
+    "offer": ["Max 3 forp/hushall"]
+  }
+]
+
+Exempel negativt fall (ska INTE splittas):
+Input-idé: "Ingredienser: tomat, lok, vitlok".
+Output-idé: en produktpost (ingen variant-expansion).
+
 Text att tolka:
 ${truncatedText}`;
   }

backend/src/flyer-import/services/flyer-normalizer.service.spec.ts

@@ -105,5 +105,41 @@ describe('FlyerNormalizerService', () => {
       const result2 = service.normalize(undefined as any);
       expect(result2).toEqual([]);
     });
+
+    it('splits listed cheese variants into separate products', () => {
+      const items = [
+        {
+          rawName: 'PRÄST®, HERRGÅRD®, GREVÉ®',
+          brand: 'ARLA KO',
+          unit: 'kg',
+          comparisonPrice: '79,90',
+          offer: ['Max 3 förp/hushåll'],
+        },
+      ];
+
+      const result = service.normalize(items);
+
+      expect(result).toHaveLength(3);
+      expect(result.map((item) => item.rawName)).toEqual(['Prastost', 'Herrgardsost', 'Greveost']);
+      expect(result.every((item) => item.brand === 'Arla Ko')).toBe(true);
+      expect(result.every((item) => item.categoryHint === 'Hårdost')).toBe(true);
+      expect(result[0].parseReasons).toContain('split_cheese_variants');
+    });
+
+    it('keeps single cheese item unsplit but normalizes brand/category', () => {
+      const items = [
+        {
+          rawName: 'Prästost',
+          brand: 'arla ko',
+        },
+      ];
+
+      const result = service.normalize(items);
+
+      expect(result).toHaveLength(1);
+      expect(result[0].rawName).toBe('Prästost');
+      expect(result[0].brand).toBe('Arla Ko');
+      expect(result[0].categoryHint).toBe('Hårdost');
+    });
   });
 });

backend/src/flyer-import/services/flyer-normalizer.service.ts

@@ -23,6 +23,11 @@ export class FlyerNormalizerService {
   private readonly logger = new Logger(FlyerNormalizerService.name);
   private readonly MAX_BUNDLE_ITEMS = 20;
   private readonly MAX_BUNDLE_ITEM_LENGTH = 120;
+  private readonly CHEESE_VARIANT_TO_NAME: Record<string, string> = {
+    prast: 'Prastost',
+    herrgard: 'Herrgardsost',
+    greve: 'Greveost',
+  };
 
   private readonly UNIT_MAPPING: Record<string, string> = {
     // Längd
@@ -61,29 +66,30 @@ export class FlyerNormalizerService {
     }
 
     return items
-      .map((item, idx) => this.normalizeItem(item, idx))
+      .flatMap((item, idx) => this.normalizeItem(item, idx))
       .filter((item): item is NormalizedFlyerItem => item !== null);
   }
 
-  private normalizeItem(item: any, index: number): NormalizedFlyerItem | null {
+  private normalizeItem(item: any, index: number): Array<NormalizedFlyerItem | null> {
     if (!item || typeof item !== 'object') {
       this.logger.warn(`Item ${index} is not an object, skipping`);
-      return null;
+      return [null];
     }
 
     const rawName = this.extractString(item.rawName) || this.extractString(item.name);
     if (!rawName) {
       this.logger.warn(`Item ${index} has no name, skipping`);
-      return null;
+      return [null];
     }
 
     const normalizedName = this.extractString(item.normalizedName) || this.normalizeName(rawName);
-
+    const normalizedBrand = this.normalizeBrand(this.extractString(item.brand), rawName);
-    return {
+    const categoryHint = this.normalizeCategory(this.extractString(item.category), rawName);
+    const baseItem: NormalizedFlyerItem = {
       rawName,
       normalizedName,
-      brand: this.extractString(item.brand),
+      brand: normalizedBrand,
-      categoryHint: this.normalizeCategory(this.extractString(item.category)),
+      categoryHint,
       price: this.extractPrice(item.price),
       priceUnit: this.normalizeUnit(this.extractString(item.unit)),
       comparisonPrice: this.extractPrice(item.comparisonPrice),
@@ -98,6 +104,13 @@ export class FlyerNormalizerService {
         ? item.reasonCodes.map(String)
         : ['normalized'],
     };
+
+    const expandedItems = this.expandCheeseVariants(baseItem);
+    if (expandedItems.length > 0) {
+      return expandedItems;
+    }
+
+    return [baseItem];
   }
 
   private extractString(val: any): string | null {
@@ -138,7 +151,10 @@ export class FlyerNormalizerService {
     return this.UNIT_MAPPING[cleaned] ?? null;
   }
 
-  private normalizeCategory(category: string | null): string | null {
+  private normalizeCategory(category: string | null, rawName?: string): string | null {
+    if (this.containsSwedishCheeseVariant(rawName)) {
+      return 'Hårdost';
+    }
     if (!category) return null;
 
     const normalized = category.trim().toLowerCase();
@@ -162,6 +178,59 @@ export class FlyerNormalizerService {
     return categoryMap[normalized] ?? null;
   }
 
+  private normalizeBrand(brand: string | null, rawName?: string): string | null {
+    const value = `${brand ?? ''} ${rawName ?? ''}`.trim().toLowerCase();
+    if (value.includes('arla ko')) {
+      return 'Arla Ko';
+    }
+    return brand;
+  }
+
+  private containsSwedishCheeseVariant(value?: string | null): boolean {
+    if (!value) return false;
+    const normalized = this.stripDiacritics(value.toLowerCase());
+    return ['prast', 'herrgard', 'greve'].some((token) => normalized.includes(token));
+  }
+
+  private expandCheeseVariants(item: NormalizedFlyerItem): NormalizedFlyerItem[] {
+    if (item.isBundle) return [];
+
+    const normalizedRaw = this.stripDiacritics(item.rawName.toLowerCase());
+    const tokens = normalizedRaw
+      .split(/[,/&]|\boch\b|\band\b/g)
+      .map((part) => part.trim())
+      .filter(Boolean);
+
+    const variants = Array.from(
+      new Set(
+        tokens
+          .map((token) => token.replace(/[^a-z0-9\s]/g, ''))
+          .flatMap((token) => Object.keys(this.CHEESE_VARIANT_TO_NAME).filter((key) => token.includes(key))),
+      ),
+    );
+
+    if (variants.length <= 1) {
+      return [];
+    }
+
+    return variants.map((variant) => {
+      const productName = this.CHEESE_VARIANT_TO_NAME[variant];
+      return {
+        ...item,
+        rawName: productName,
+        normalizedName: this.normalizeName(productName),
+        categoryHint: 'Hårdost',
+        parseReasons: [...item.parseReasons, 'split_cheese_variants'],
+      };
+    });
+  }
+
+  private stripDiacritics(value: string): string {
+    return value
+      .normalize('NFD')
+      .replace(/[\u0300-\u036f]/g, '');
+  }
+
   private normalizeOfferText(offer: any): string | null {
     if (!offer) return null;