feat(update): UpToDate-Status mit temporärem Feedback anzeigen

- Neuer UpdateStatus.UpToDate State
- Button zeigt 'Keine Updates gefunden' für 5 Sekunden
- Mindestens 1s Checking-Anzeige (vermeidet Flicker bei schneller Antwort)
- UpdateBanner blendet UpToDate-Status aus

app/src/main/java/de/bollwerk/app/ui/settings/SettingsScreen.kt

@@ -458,6 +458,21 @@ internal fun SettingsScreen(
                             Text("Suche nach Updates…")
                         }
                     }
+                    is UpdateStatus.UpToDate -> {
+                        OutlinedButton(
+                            onClick = {},
+                            enabled = false,
+                            modifier = Modifier.fillMaxWidth()
+                        ) {
+                            Icon(
+                                imageVector = Icons.Default.SystemUpdate,
+                                contentDescription = null,
+                                modifier = Modifier.size(18.dp)
+                            )
+                            Spacer(modifier = Modifier.width(8.dp))
+                            Text("Keine Updates gefunden")
+                        }
+                    }
                     is UpdateStatus.Available -> {
                         Button(
                             onClick = updateViewModel::startDownload,

app/src/main/java/de/bollwerk/app/ui/update/UpdateBanner.kt

@@ -32,7 +32,8 @@ internal fun UpdateBanner(
     onDismiss: () -> Unit,
     modifier: Modifier = Modifier
 ) {
-    val isVisible = status !is UpdateStatus.Hidden && status !is UpdateStatus.Checking && status !is UpdateStatus.Available
+    val isVisible = status !is UpdateStatus.Hidden && status !is UpdateStatus.Checking
+        && status !is UpdateStatus.Available && status !is UpdateStatus.UpToDate
 
     AnimatedVisibility(
         visible = isVisible,

app/src/main/java/de/bollwerk/app/ui/update/UpdateUiState.kt

@@ -7,6 +7,7 @@ internal data class UpdateUiState(
 internal sealed interface UpdateStatus {
     data object Hidden : UpdateStatus
     data object Checking : UpdateStatus
+    data object UpToDate : UpdateStatus
     data class Available(val versionName: String, val versionCode: Int, val apkUrl: String) : UpdateStatus
     data class Downloading(val progress: Float) : UpdateStatus
     data class ReadyToInstall(val versionName: String, val versionCode: Int) : UpdateStatus

app/src/main/java/de/bollwerk/app/ui/update/UpdateViewModel.kt

@@ -10,6 +10,7 @@ import de.bollwerk.app.domain.model.UpdateCheckResult
 import de.bollwerk.app.domain.repository.UpdateRepository
 import de.bollwerk.app.domain.usecase.ApkInstaller
 import de.bollwerk.app.domain.usecase.CheckForUpdateUseCase
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
@@ -36,7 +37,12 @@ internal class UpdateViewModel @Inject constructor(
     fun checkForUpdate() {
         viewModelScope.launch {
             _uiState.update { it.copy(status = UpdateStatus.Checking) }
-            when (val result = checkForUpdateUseCase(BuildConfig.VERSION_CODE)) {
+            val startTime = System.currentTimeMillis()
+            val result = checkForUpdateUseCase(BuildConfig.VERSION_CODE)
+            val elapsed = System.currentTimeMillis() - startTime
+            if (elapsed < 1000) delay(1000 - elapsed)
+
+            when (result) {
                 is UpdateCheckResult.UpdateAvailable -> {
                     _uiState.update {
                         it.copy(
@@ -50,6 +56,8 @@ internal class UpdateViewModel @Inject constructor(
                 }
                 is UpdateCheckResult.UpToDate,
                 is UpdateCheckResult.NotConfigured -> {
+                    _uiState.update { it.copy(status = UpdateStatus.UpToDate) }
+                    delay(5000)
                     _uiState.update { it.copy(status = UpdateStatus.Hidden) }
                 }
                 is UpdateCheckResult.Error -> {