Consider sharing Supabase auth response types

## Summary
The CLI defines  and  in . These describe the Supabase REST auth responses we also handle in other projects.

## Proposal
Move these response types into  (e.g., under ) so they can be reused by other clients (API server, web) when/if needed.

## Notes
- Today only the CLI uses them, so there is no urgency.
- Opening this issue to track the idea and decide once other consumers appear.