OIDC / OAuth

To do!

See also

• https://accounts.google.com/.well-known/openid-configuration

• https://next-auth.js.org/configuration/providers/oauth

[ToDo] Basically just clone shop.markmoriarty.com and strip out all the non-auth pages (/users, /protected, etc.) — leave the "login page" and redirect after login. Rough schematic (replace GitHub with LoginWithLink).