Package output renders command results as a human table or as machine JSON
or YAML, selected by the --format flag. Agents pass --format json for a
stable, parseable surface.
func Emit(format string, v interface{}, tableFn func() Table) error
Emit writes v in the requested format. For "table" it calls tableFn to build
the columns; for "json"/"yaml" it marshals v directly. tableFn may be nil
when only structured output makes sense.