Investigate memory issues

Our app process for https://clojurians-log.clojureverse.org/ keeps running out of memory.

I've already done some investigation with `jmap` and `visualvm` to find some places where memory might be leaking.


We need to figure out what exactly is causing this, or if we simply have too little ram?

Last ditch effort would be to move away from datomic to postgresql, but since datomic handles so many production instances well, I think we can figure out the problem and solve it.

### Temporary fix

Simply restarting the app server resolves the issue for a couple days (a week or so) before OOM error happens again. But this causes some problems with cloudflare caching, so we don't want to rely on this for long.

Start with the existing jmap and VisualVM investigation, then observe the app process as memory grows toward an OOM over several days. Determine whether a specific leak or insufficient RAM is responsible, and validate a lasting remediation rather than relying on server restarts.

Written by the indexing model from the issue text.