One-time setup. Takes about 5 minutes.
Go to supabase.com, sign up (free), and create a new project. Choose a strong database password and remember which region you picked.
In your Supabase project, go to SQL Editor and paste/run the SQL below. This creates all tables and a default admin user.
In Supabase, go to Project Settings → API. Copy your Project URL and anon public key.
After saving, log in with username admin and password admin. Change this immediately from the Users tab.