Firebase Setup Required — prices won't sync across devices until this is done

1. Go to console.firebase.google.com and click Add project
2. Enter any project name (e.g. arora-sweets), click through and create the project
3. In the left sidebar click Build → Realtime Database → Create Database
4. Choose any location and select Start in test mode → Enable
5. Copy the Database URL shown at the top (looks like https://arora-sweets-default-rtdb.firebaseio.com)
6. Go to Project Settings (gear icon) → General → copy the Web API Key
7. Open the file js/firebase-config.js and paste the URL into dbUrl and the key into apiKey
8. Go to Build → Authentication → Sign-in method and enable Email/Password
9. Go to Build → Authentication → Users → Add user and create the owner's login (email + password)
10. Go to Build → Realtime Database → Rules and set rules that restrict writes to that owner account (see project README/notes for the exact rules JSON)
11. Save the file, deploy/upload your site, then refresh this page and sign in with the owner email/password