Db user setup

[FlynnOConnell]

Main user registration validation logic:

• POST request validation, match custom errors to http status
• Response handling from matching http response status
• Backend 404 catch
• Segregate logic and modularization
• Improve database naming conventions and migrations
• Docker compose dev scripts
• Clean deps and dead code
• Template for frontend conditional component rendering

[LukeBrandon]

Resolved all requested changes.

I did ignore one suggestion about:

Ok(Created::new(location) because this is exactly what I did, just not in the commented function. I think leaving the logic to attempt the "create_user" query, and the logic to handle the resulting responses from that query are better left separate. signup_user handles that logic in the current version.

I didn't realize it was being called by something else, that is good then