MAJOR UPPDATE: "First Ai"

feat: add AI categorization for products and enhance user management

- Integrated AI service for category suggestions in receipt import and product management.
- Added premium subscription feature for users with corresponding API endpoints.
- Implemented admin interface for managing pending product suggestions.
- Enhanced user management to include premium status and corresponding UI updates.
- Updated database schema to support new fields for premium status and product status.

backend/src/receipt-import/dto/parsed-receipt-item.dto.ts

@@ -1,3 +1,5 @@
+import type { CategorySuggestion } from '../../ai/ai.service';
+
 export interface ParsedReceiptItem {
   rawName: string;
   quantity: number;
@@ -9,4 +11,6 @@ export interface ParsedReceiptItem {
   // ordbaserad match: förslag, kräver bekräftelse
   suggestedProductId?: number;
   suggestedProductName?: string;
+  // AI-kategorisuggestion för ej matchade varor (premium)
+  categorySuggestion?: CategorySuggestion;
 }