Stage 11: Store and change products in MongoDB
JDK 21+; Maven 3.9+.
Open the folder containing pom.xml.
Start MongoDB locally on 27017 or set MONGODB_URI and MONGODB_DATABASE for Atlas. See README.html.
Run: mvn spring-boot:run
Open: http://localhost:8089/products
Stop: Ctrl+C
Complete explanations and all source: README.html
Expected: Fresh database: 30 rows, 29 in stock. Create ID 31: 31 total. Set its stock to 0: still 31 total, 29 in stock. Restart: ID 31 still has stock 0. Delete ID 31: 30 total and its details URL returns 404.
