Enable Spring Boot Actuator with limited exposure and secure /actuator/mappings endpoint access.

backend/src/main/resources/application.properties

@@ -19,3 +19,4 @@ spring.mail.properties.mail.smtp.auth=true
 spring.mail.properties.mail.smtp.ssl.enable=true
 spring.mail.properties.mail.smtp.socketFactory.class=javax.net.ssl.SSLSocketFactory
 chat.allowed-ip=${ALLOWED_IP:10.0.0.0/24}
+management.endpoints.web.exposure.include=mappings