Challenge 1: Application and Activity Setup — Solution

// MyApplication.kt
@HiltAndroidApp
class MyApplication : Application()

// AndroidManifest.xml — inside <application>
<application
    android:name=".MyApplication"
    android:theme="@style/Theme.MyFirstApp"
    ... >
    ...
</application>

// MainActivity.kt
@AndroidEntryPoint
class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            // Hilt-injected composables/ViewModels can be used here
        }
    }
}

// What would go wrong without @AndroidEntryPoint:
// If MainActivity used hiltViewModel() to obtain a @HiltViewModel-
// annotated ViewModel but MainActivity itself was NOT annotated with
// @AndroidEntryPoint, the app would crash at runtime with an error
// indicating Hilt could not find an entry point / the Activity isn't
// part of Hilt's dependency graph. @AndroidEntryPoint is what actually
// wires a specific Activity (or Fragment) INTO Hilt's dependency
// injection system — @HiltAndroidApp alone only sets up the app-wide
// container, it doesn't automatically make every Activity injectable.

Notes:
- android:name=".MyApplication" in the manifest is what tells Android to
  actually instantiate MyApplication (rather than the default generic
  Application class) when the app process starts — @HiltAndroidApp alone
  on the class does nothing unless it's actually registered this way.
- @AndroidEntryPoint is required on EVERY Activity/Fragment that uses
  Hilt injection, not just the launcher Activity — a multi-screen app
  needs this annotation repeated on each one that needs it.