Better observability

[senekor]

Let's send our logs to a monitoring service via OpenTelemetry. One option for a self-hosted monitoring service would be Jaeger.

https://broch.tech/posts/rust-tracing-opentelemetry/

Originally posted by @remlse in #30 (comment)

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Currently, our tracing logs go to stdout and can be retrieved via journalctl, since we deploy as a systemd service. Sifting through the logs could be much nicer.

Apart from a little enabling work in buenzlimarks itself, I suspect the bigger task would be to self-host Jaeger and wire everything up in the deployment repo.