Please add sign-in to this app.

1. Read blackwall://auth and blackwall://access-rules.
2. Check the address and the publishable key with get_project_keys { ref, only: "publishable" }. Use only the publishable key in the frontend.
3. Sign-up and sign-in are /auth/v1/signup and /auth/v1/token?grant_type=password.
4. If there is per-user data, give the table a user_id,
   and set access rules with auth_<ref>.uid() so each user sees only their own rows.
5. Create a test account with add_user, and check that it cannot see other people's rows.

Leave out step 4 and sign-in works, but every user sees everyone else's data.

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https://end.blackall.ai/docs/how/add-login?lang=en