Secure Firebase login — Admin / User access
Firebase Console ke Web App ka config yahan paste karein. Ye config password/secret nahi hota.
First Admin: Firebase Console me pehle Email/Password user banayein, phir users/{UID} document me role: admin set karein. Uske baad Admin panel se normal Users create kiye ja sakte hain.
Admin yahan se BillBook users create kar sakta hai. Password Firebase Authentication handle karta hai; plain password database me save nahi hota.