Research: User auth

[fennifith]

We want to allow users to create an account and sign into Playful Programming using https://www.better-auth.com/ (primarily with GitHub OAuth)

Look into using https://github.com/flaviodelgrosso/fastify-better-auth to enable this on the BE + the better-auth client through Preact on the FE.

Possible concerns:

• I'm not sure about exposing a bunch of better-auth APIs under /api/auth - the prefix seems a bit arbitrary (won't be consistent with other endpoints) and won't show up in the docs (maybe this is okay?).
• It seems like there is potential for those to overlap with our own endpoints if we're not careful.
• If there's a way to customize the prefix for these endpoints, that would solve my concerns!

[meows]

BetterAuth allows you to customize a bit.

• endpoint
• schema
  • table name
  • additional properties