fix: add camel-management to plain-app for JMX metrics

Without camel-management on the classpath, the JMX management agent
is null and JmxMetricsBridge skips metrics entirely.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-plain-app/pom.xml

@@ -32,6 +32,10 @@
             <groupId>org.apache.camel</groupId>
             <artifactId>camel-direct</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.apache.camel</groupId>
+            <artifactId>camel-management</artifactId>
+        </dependency>
 
         <!-- Logging: Logback (explicit, no framework provides it) -->
         <dependency>