refactor(ping-feature): clean up imports, simplify UI state handling, and remove redundant variables

Simplified imports for better readability, addressed unnecessary null check for `uiState.errorMessage`, and removed an unused `CoroutineScope` variable in `MainApp`. Improved code clarity and maintainability.

frontend/features/ping-feature/src/commonMain/kotlin/at/mocode/ping/feature/presentation/PingScreen.kt

@@ -48,7 +48,7 @@ fun PingScreen(viewModel: PingViewModel) {
             style = MaterialTheme.typography.titleMedium,
             color = MaterialTheme.colorScheme.error
           )
-          Text(text = uiState.errorMessage ?: "")
+          Text(text = uiState.errorMessage)
           Button(onClick = { viewModel.clearError() }) {
             Text("Clear")
           }

frontend/features/ping-feature/src/commonTest/kotlin/at/mocode/ping/feature/integration/PingSyncIntegrationTest.kt

@@ -1,17 +1,13 @@
 package at.mocode.ping.feature.integration
 
 import at.mocode.frontend.core.sync.SyncManager
-import at.mocode.ping.api.PingEvent
 import at.mocode.ping.feature.domain.PingSyncServiceImpl
 import at.mocode.ping.feature.test.FakePingEventRepository
-import io.ktor.client.HttpClient
-import io.ktor.client.engine.mock.MockEngine
-import io.ktor.client.engine.mock.respond
-import io.ktor.client.plugins.contentnegotiation.ContentNegotiation
-import io.ktor.http.HttpHeaders
-import io.ktor.http.HttpStatusCode
-import io.ktor.http.headersOf
-import io.ktor.serialization.kotlinx.json.json
+import io.ktor.client.*
+import io.ktor.client.engine.mock.*
+import io.ktor.client.plugins.contentnegotiation.*
+import io.ktor.http.*
+import io.ktor.serialization.kotlinx.json.*
 import kotlinx.coroutines.test.runTest
 import kotlinx.serialization.json.Json
 import kotlin.test.Test

frontend/shells/meldestelle-portal/src/commonMain/kotlin/MainApp.kt

@@ -36,7 +36,7 @@ fun MainApp() {
       val authApiClient = koinInject<AuthApiClient>()
       // Delta-Sync blueprint: resolve the Ping feature view model via Koin.
       val pingViewModel: PingViewModel = koinViewModel()
-      val scope = rememberCoroutineScope()
+      rememberCoroutineScope()
 
       // Handle PKCE callback on an app load (web)
       LaunchedEffect(Unit) {