test: the notifications view model is built inside each test, after the test Main dispatcher is set (#6275)

Built as a property initializer it ran at class construction, before
MainDispatcherExtension's beforeEach, so viewModelScope.launch in init hit
the missing Main dispatcher. Its uncaught exceptions also failed the next
coroutine test in the JVM (RetryTransientIoTest).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

android/app/src/test/java/com/fabledsword/minstrel/notifications/ui/NotificationsViewModelTest.kt

@@ -24,7 +24,8 @@ class NotificationsViewModelTest {
     private val network: NetworkStatusController = mockk {
         every { state } returns MutableStateFlow(ServerHealth.Healthy)
     }
-    private val viewModel = NotificationsViewModel(repository, network)
+    // Lazy: built inside each test, after the extension has swapped in the test Main dispatcher.
+    private val viewModel by lazy { NotificationsViewModel(repository, network) }
 
     private fun row(id: String, read: Boolean) = CachedNotificationEntity(
         id = id,