Collect analytics + allow managing privacy requests

[nonprofittechy]

We should eventually have an admin backend that allows us to view and manage litigant sessions. Our terms of service promise a way to delete user information, and that seems to make sense following California privacy laws and GDRP best practices.

Alongside this, the admin backend should expose some way to view aggregate usage information that is saved persistently so we can share it out in reports. The usage data should mostly be anonymous

[nonprofittechy]

Another, probably related thought: we might want to collect data about what people like/dislike about the tool too (e.g., a short survey)