Feat: Added support for switching to ECS conformant JSON logging.

[buddemat]

Goal: Make cadenzaanalytics logging configurable to emit Elastic Common Schema (ECS) JSON, suitable for container log aggregation, covering the library itself, dependent packages, and analytics extension code — with minimal burden on extension developers.

Changes:

• moved loggin to new file src/cadenzaanalytics/logging_config.py
• added CadenzaEcsFormatter as subclass of ecs_logging.StdlibFormatter and stamping every record with service.name/service.version
• explicitly re-pointting gunicorn.error/gunicorn.access at the same handler
• documentation and tests

[DanDits]

Looks fine, I like having the two options and an easy switch so local development is not affected. Looks like you tried to work around some gunicorn quirks at best effort. Do the mentioned non-json lines that might be logged bother a potential json-expecting log consumer?