Switch to structured json logging

Manage's current log files are hard to parse because of custom messaging and multi-line logs.  Please switch to structured (json) logging so it get easier to parse the messages to backend systems.

Sprint boot seems to support both Elastic and Logstash formats (https://spring.io/blog/2024/08/23/structured-logging-in-spring-boot-3-4).  The ECS/Elastic format seems most flexible, so please use that,