Add cqrs module: CQRS in Spring Boot Without a Framework

Separate write/read DataSources, a JPA command side, and two interchangeable
projection listeners (sync and @Async) demonstrating the real latency-versus-
freshness trade-off CQRS forces. Includes a reflection-based proof that the
query side has no dependency on the write side, and a real failure/fix
transcript for the -parameters compiler flag this standalone reactor doesn't
inherit from spring-boot-starter-parent.

pom.xml

@@ -15,6 +15,7 @@
     Each Maven module backs one post; modules are added over time, one commit each.
     - order-fulfillment : Spring Modulith 2.1: Enforcing Module Boundaries Inside a Spring Boot Monolith
     - outbox            : Transactional Outbox with the Spring Modulith Event Publication Registry
+    - cqrs              : CQRS in Spring Boot Without a Framework: Separate Read Models and Projections
   </description>
 
   <properties>
@@ -27,5 +28,6 @@
   <modules>
     <module>order-fulfillment</module>
     <module>outbox</module>
+    <module>cqrs</module>
   </modules>
 </project>