initial commit of membership endpoint

[ricklarsen]

What/Why/How?

Initial pass at creating a membership system with multiple tiers for museum patrons.

issue #17

Submitted for feedback!

Reference

Testing

Screenshots (optional)

Check yourself

• [ ] Code is linted
• [ ] Tested with redoc/reference-docs/workflows (internal)
• [ ] All new/updated code is covered with tests

Security

• [ ] Security impact of change has been considered
• [ ] Code follows company security practices and guidelines