chore(alerting): add jmustache 1.16

Declared in cameleer-server-core pom (canonical location for unit-testable
rendering without Spring) and mirrored in cameleer-server-app pom so the
app module compiles standalone without a full reactor install.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cameleer-server-app/pom.xml

@@ -82,6 +82,11 @@
             <artifactId>org.eclipse.xtext.xbase.lib</artifactId>
             <version>2.37.0</version>
         </dependency>
+        <dependency>
+            <groupId>com.samskivert</groupId>
+            <artifactId>jmustache</artifactId>
+            <version>1.16</version>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-validation</artifactId>