Seven implemented stages, in order:
1: hello-spring-simple
2: spring-controller
3: spring-request-params
4: spring-path-variables
5: spring-calculator-basic
6: spring-products-thymeleaf
7: spring-calculator

Each README.html ends with the keywords from that stage.
Stages 8-12 are a planned roadmap, not included runnable projects.
Requires JDK 21+ and Maven 3.9+. Set an available port in application.properties.
Run beside pom.xml: mvn spring-boot:run
Tutorial: https://edupoly.in/tutorials/java-spring/foundations.html#beginner-stages
