feat: add rematch functionality for recipe ingredients and enhance inventory management

- Added a new API path for rematching recipe ingredients in `api_paths.dart`.
- Implemented a manual product creation dialog in `inventory_screen.dart` to allow users to create new products directly.
- Integrated the rematch functionality in `recipe_repository.dart` to handle rematching of recipe ingredients.
- Updated the recipe detail screen to include a button for triggering the rematch process.
- Introduced a new `RecipeMatchingService` in the backend to handle ingredient matching logic.
- Added database migration to include `aiEngineEnabled` column in the User table.

Co-authored-by: Copilot <copilot@github.com>

backend/prisma/schema.prisma

@@ -17,6 +17,7 @@ model User {
   role         String       @default("user")
   isPremium    Boolean      @default(false)
   canShareRecipes Boolean   @default(true)
+  aiEngineEnabled Boolean   @default(false)
   createdAt    DateTime     @default(now())
   updatedAt    DateTime     @updatedAt