Add and improve logging

- [ ] Replace all instances of std log with apex/log
- [ ] Replace all instances of `fmt.Print*()` with apex/log
- [ ] Replace all instances of any other form of logging with apex/log
- [ ] Add logging where appropriate
- [ ] `app/bot/registry`
- [ ] etc

Search the Go repository for uses of std log, fmt.Print*(), and other logging forms, then inspect app/bot/registry as the first named area. Done means the identified logging uses consistently use apex/log and appropriate logging has been added where needed, though the issue does not define the remaining scope.

Written by the indexing model from the issue text.