Develop a secure, offline-capable Flutter app that allows teachers to: Log in using UserID + Password Verify login using Google Authenticator (2FA) Manage subject-wise attendance View attendance analytics Sync data online & offline Core Features (Must-Have) Authentication UserID + Password login (NO email, NO phone) Google Authenticator (TOTP 2FA) Secure session handling Teacher Dashboard List of assigned subjects Manual Refresh button (online sync) Background auto-sync Sync status indicator Subject Dashboard Attendance summary (Present / Absent %) Bar chart showing count of attendance sessions per subject Tabs: Daily / Weekly / Monthly Buttons: Take Attendance Generate Report Take Attendance Student list or grid Present / Absent toggle Offline support Save attendance locally Sync when online Reports Student-wise report: Student ID Name Present count Absent count Charts & Analytics Bar chart using fl_chart Subject-level attendance session counts Dynamic update on refresh & sync Sync & Offline Offline-first design Local storage (Hive / SQLite) Background sync (WorkManager) Sync on: Manual refresh Internet reconnect Periodic background job Tech Stack (Preferred) Flutter (latest stable) State management: Riverpod / Bloc / Provider Charts: fl_chart Local DB: Hive / SQLite Backend: REST API