Add lightweight SSO so the app can learn the current user's name and email without a full account system.
Scope for this issue:
- Integrate an OIDC provider (e.g. Auth0, Cognito, or Cloudflare Access)
- Pre-fill the first participant's name from the user's profile on load
- Store a user ID in state so a future backend can associate bills with accounts
Out of scope (separate issues):
- Remote bill storage (S3, DynamoDB, Cloudflare KV, etc.)
- Sharing bills with other users
No remote backend or auth in the current version — this issue is forward-looking context.
Add lightweight SSO so the app can learn the current user's name and email without a full account system.
Scope for this issue:
Out of scope (separate issues):
No remote backend or auth in the current version — this issue is forward-looking context.