refactor(dynamic): add multi-method support to RouteShape, update framework bindings, and improve test coverage

tests/dynamic_fixtures/message_handler/kafka_java/Vuln.java

@@ -1,13 +1,11 @@
 // Phase 20 (Track M.2) — Kafka Java vuln fixture.
-//
-// Marker line so the kafka-java framework adapter binds:
-// `org.springframework.kafka` consumer entry point.  Annotation is
-// elided so javac compiles without the Spring jar; the dynamic harness
-// invokes onMessage reflectively.
+
+import org.springframework.kafka.annotation.KafkaListener;
 
 public class Vuln {
     public Vuln() {}
 
+    @KafkaListener(topics = "orders")
     public void onMessage(String body) throws Exception {
         // SINK: tainted body concatenated into shell command
         new ProcessBuilder("sh", "-c", "echo " + body).inheritIO().start().waitFor();