Is your feature request related to a problem? Please describe.
Currently every information is dumped as a single line of text, using fmt.Sprintf to embed information and variable. This is hard to parse by third party application, such as Grafana/Loki.

Describe the solution you'd like
Utilize a standard logfmt that is easy to read and parse. This is already supported by slog. Even better if it can be configured to use json in case somebody wants that. ( slog has that option too. )

Describe alternatives you've considered
slog seems to be a straight choice, it's already used and supports this feature. Only thing needed to be changed is the approach of the logs.

Additional context
Would be nice to provide some additional context if possible. Such as when using the foreground feature, it could add the id of the cron job to the context by default.