Support authentication without database sessions (i.e. JWT)

### What do you want and why?

Server-side sessions come with pros and cons. Some users prefer the tradeoffs/benefits provided by client-side sessions (e.g. JWT).

This also makes it easier to choose alternative data stores (such as those unsupported by Prisma) without having to modify the auth system.

### Possible implementation(s)

Today database sessions are assumed. It would be nice to allow the user to select the session management style during project generation, then generate the project files accordingly.

### Additional context

- [JWT RFC](https://datatracker.ietf.org/doc/html/rfc7519)

Start by reviewing the project-generation flow and the current database-session assumptions described in the issue, including how Prisma is used. Done means users can choose a session-management style during generation and receive project files that support JWT-based sessions without requiring database sessions.

Written by the indexing model from the issue text.