metrics: chat events (#461)
* update status definitions
* delete more useless things
* refactor first
* .
* old tests passing
* making progress
* agent_id needs to be in the body
* tests passing again
* progress
* add duration
* fix type error
* fix tests and type errors
* wow a working test!
* lint
* leave todos
* address self comments
* enforce assistant id in chats, defaulting when needed
* update makefile
* fix user creation event
* revert unneeded changes
* pass in assistant!
