chore(ci): update project documentation and flyer import features

Update project documentation with recent CI improvements and flyer import enhancements:

- Add ESLint configuration for backend and Dart lints for Flutter
- Document Prisma query logging via PRISMA_LOG_QUERIES environment variable
- Update NEXT_STEPS.md, README.md, and TEKNISK_BESKRIVNING.md with new features
- Add isOffer, offerLimitText, comparisonPrice, comparisonUnit, parseConfidence, and parseReasons fields to FlyerImportItem
- Update FlyerImportResponse type to include new fields
- Extend file picker to support image formats (png, jpg, jpeg, webp)
- Add offer badge display and price formatting in Flutter UI
- Implement PDF preview functionality for flyer import

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

@@ -1,28 +1,30 @@
-export type FlyerImportMatchVia = 'alias' | 'exact' | 'token' | 'none';
-
-export type FlyerImportItem = {
-  flyerItemId: number | null;
-  rawName: string;
-  normalizedName: string;
-  category: string | null;
-  price: number | null;
-  priceUnit: string | null;
-  comparisonPrice: number | null;
-  comparisonUnit: string | null;
-  offerText: string | null;
-  parseConfidence: number;
-  parseReasons: string[];
-  matchedProductId: number | null;
-  matchedProductName: string | null;
-  matchedVia: FlyerImportMatchVia;
-  matchConfidence: number;
-  matchReasons: string[];
-};
-
-export type FlyerImportResponse = {
-  sessionId: number | null;
-  retailer: 'willys';
-  parserVersion: 'v1';
-  items: FlyerImportItem[];
-  warnings: string[];
-};
+export type FlyerImportMatchVia = 'alias' | 'exact' | 'token' | 'none';
+
+export type FlyerImportItem = {
+  flyerItemId: number | null;
+  rawName: string;
+  normalizedName: string;
+  category: string | null;
+  price: number | null;
+  priceUnit: string | null;
+  comparisonPrice: number | null;
+  comparisonUnit: string | null;
+  offerText: string | null;
+  isOffer: boolean;
+  offerLimitText: string | null;
+  parseConfidence: number;
+  parseReasons: string[];
+  matchedProductId: number | null;
+  matchedProductName: string | null;
+  matchedVia: FlyerImportMatchVia;
+  matchConfidence: number;
+  matchReasons: string[];
+};
+
+export type FlyerImportResponse = {
+  sessionId: number | null;
+  retailer: 'willys';
+  parserVersion: 'v1';
+  items: FlyerImportItem[];
+  warnings: string[];
+};