feat: add unit mapping functionality

- Added new API path for unit mappings in `api_paths.dart`.
- Implemented `upsertUnitMapping` method in `ImportRepository` to handle unit mapping creation.
- Updated `ReceiptImportTab` to learn and save unit mappings during receipt import.
- Created DTO for unit mapping with validation in `create-unit-mapping.dto.ts`.
- Added SQL migration for `UnitMapping` table creation with necessary constraints.

backend/dist/products/products.service.js

@@ -40,7 +40,7 @@ let ProductsService = class ProductsService {
     }
     async findByOwner(userId) {
         return this.prisma.product.findMany({
-            where: { ownerId: userId, isPrivate: true, isActive: true },
+            where: { ownerId: userId, isActive: true },
             select: { id: true, name: true, canonicalName: true, categoryId: true },
             orderBy: { name: 'asc' },
         });