Migrate MainActivity layout to a full Compose NavHost

Convert MainActivity from AppCompatActivity to ComponentActivity and replace XML layouts with setContent.
Remove activity_main.xml and nav_graph.xml, migrating navigation logic to a Compose-based NavHost.
Implement routing using LaunchedEffect to reactively navigate between LoginScreen and HomeScreen based on authentication state.
Replace fragment-based UI with LoginScreen and HomeScreen composables.
Introduce LoadingScreen and LoadingOverlay composables to manage UI state during session initialization and background processing.
Clean up View-based dependencies including Data Binding and NavHostFragment.

MIGRATION | #22 MainActivity to Jetpack Compose and Compose Navigation

Navigation Menu