Add user registration with email verification

[happyseaurchin]

What's Needed

A registration flow so multiple users can create accounts and connect to characters. Currently the system has no auth — anyone who opens the app is anonymous.

Flow

1. User enters email
2. System sends verification code/link (Supabase Auth handles this)
3. User confirms → account created
4. User can then create/select a character

Technical Context

• Supabase Auth is already in the stack (project: piqxyfmzzywxzqkzmpmm)
• Frontend is React + TypeScript
• Supabase client is configured in src/lib/supabase.ts
• See Supabase Auth docs: https://supabase.com/docs/guides/auth

What Exists Already

• Supabase project with real-time subscriptions working
• Character table exists in the database
• The connection between auth user → character needs to be built

Acceptance Criteria

• User can register with email
• Email verification works
• Authenticated user can access the app
• Unauthenticated visitors see a login/register screen

Labels

enhancement good first issue help wanted

[Gannu456]

Hey @happyseaurchin, I think I can work on this feature if you allow me to step in and think together.