Add corpse addition CLI for easier maintenance

[victorfrye]

Is your feature request related to a problem? Please describe. Why should people be modifying the JSON directly at all?? Just script it.

Describe the solution you'd like A custom script which alters the corpses JSON document and appends a newly killed product. This should be exposed as a node script in packages.json and query the user for the required data. It should also validate the information input to ensure it matches expectations and reduce rework after someone submits a new corpse.

Describe alternatives you've considered Just don't. This is a QoL enhancement, we either do or do not add it.

Additional context

• Relates to and builds upon #126