feat(ui): add test notification preference and optimize Android TV logic

Introduce a "Test Notification" preference in the settings menu to allow users to verify the notification system. This preference is automatically hidden on Android TV devices to maintain a clean UI.

Additionally, refactor notification permission handling to skip requests on Android TV and improve the internal check for Leanback support using a lazy property.

Updated string resources for the new preference across all supported languages.

app/src/main/java/com/michatec/radio/MainActivity.kt

@@ -35,17 +35,16 @@ class MainActivity : AppCompatActivity() {
     /* Main class variables */
     private lateinit var appBarConfiguration: AppBarConfiguration
 
+    // Check if the device running the app is an Android TV instance
+    private val isAndroidTV: Boolean by lazy {
+        packageManager.hasSystemFeature(PackageManager.FEATURE_LEANBACK)
+    }
+
     // request notification permission (for Android 13+)
     private val permissionLauncher = registerForActivityResult(
         ActivityResultContracts.RequestPermission()
     ) { isGranted ->
-        if (isGranted) {
-            NotificationSys.showNotification(
-                this, 
-                R.string.app_name, 
-                R.string.notification_test_content
-            )
-        } else {
+        if (!isGranted) {
             Snackbar.make(
                 findViewById(android.R.id.content),
                 R.string.snackbar_failed_permission_notification, 
@@ -95,7 +94,7 @@ class MainActivity : AppCompatActivity() {
         supportActionBar?.hide()
 
         // TV-specific loading logic: Hide the overlay once the app is ready
-        if (packageManager.hasSystemFeature(PackageManager.FEATURE_LEANBACK)) {
+        if (isAndroidTV) {
             Handler(Looper.getMainLooper()).postDelayed({
                 hideLoadingOverlay()
             }, 1200)
@@ -107,14 +106,8 @@ class MainActivity : AppCompatActivity() {
         PreferencesHelper.registerPreferenceChangeListener(sharedPreferenceChangeListener)
 
         // request permissions
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+        if (!isAndroidTV && Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
             permissionLauncher.launch(Manifest.permission.POST_NOTIFICATIONS)
-        } else {
-            NotificationSys.showNotification(
-                this, 
-                R.string.app_name, 
-                R.string.notification_test_content
-            )
         }
     }
 

app/src/main/java/com/michatec/radio/SettingsFragment.kt

@@ -22,6 +22,8 @@ import com.michatec.radio.dialogs.PresetSelectionDialog
 import com.michatec.radio.dialogs.ThemeSelectionDialog
 import com.michatec.radio.dialogs.YesNoDialog
 import com.michatec.radio.helpers.*
+import com.michatec.radio.NotificationSys
+import android.content.pm.PackageManager
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers.IO
 import kotlinx.coroutines.launch
@@ -38,6 +40,11 @@ class SettingsFragment : PreferenceFragmentCompat(), YesNoDialog.YesNoDialogList
     /* Define log tag */
     private val TAG: String = SettingsFragment::class.java.simpleName
 
+    // Check if the device running the app is an Android TV instance
+    private val isAndroidTV: Boolean by lazy {
+        packageManager.hasSystemFeature(PackageManager.FEATURE_LEANBACK)
+    }
+
     /* Overrides onViewCreated from PreferenceFragmentCompat */
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
@@ -309,6 +316,21 @@ class SettingsFragment : PreferenceFragmentCompat(), YesNoDialog.YesNoDialogList
             return@setOnPreferenceClickListener true
         }
 
+        // set up "Test Notification" preference
+        val preferenceTestNotification = Preference(context)
+        preferenceTestNotification.title = getString(R.string.pref_test_notification_title)
+        preferenceTestNotification.setIcon(R.drawable.ic_notification_app_icon_white_24dp)
+        preferenceTestNotification.summary = getString(R.string.pref_test_notification_summary)
+        preferenceTestNotification.setOnPreferenceClickListener {
+            // show test notification
+            NotificationSys.showNotification(
+                context,
+                getString(R.string.pref_test_notification_title),
+                getString(R.string.notification_test_content)
+            )
+            return@setOnPreferenceClickListener true
+        }
+
         // set up "Security" preference
         val preferenceSecurity = Preference(context)
         preferenceSecurity.title = getString(R.string.pref_security_title)
@@ -364,6 +386,10 @@ class SettingsFragment : PreferenceFragmentCompat(), YesNoDialog.YesNoDialogList
         preferenceCategoryGeneral.addPreference(preferenceThemeSelection)
         preferenceCategoryGeneral.addPreference(preferenceLanguageSelection)
 
+        if (!isAndroidTV) {
+            preferenceCategoryGeneral.addPreference(preferenceTestNotification)
+        }
+
         screen.addPreference(preferenceCategoryAudioEffects)
         preferenceCategoryAudioEffects.addPreference(preferenceBassBoost)
         preferenceCategoryAudioEffects.addPreference(preferenceReverb)

app/src/main/res/values-da/strings.xml

@@ -86,6 +86,8 @@
     <string name="pref_theme_selection_title">App-tema</string>
     <string name="pref_update_station_images_summary">Download nyeste stationsbilleder.</string>
     <string name="pref_update_station_images_title">Opdater stationsbilleder</string>
+    <string name="pref_test_notification_title">Testmeddelelse</string>
+    <string name="pref_test_notification_summary">Test om meddelelsessystemet virker.</string>
     <!-- App-genveje -->
     <string name="shortcut_last_station_disabled_message">Genvej til seneste station er deaktiveret.</string>
     <string name="shortcut_last_station_long_label">Afspil seneste station</string>

app/src/main/res/values-de/strings.xml

@@ -95,6 +95,8 @@
     <string name="pref_theme_selection_title">App-Design</string>
     <string name="pref_update_station_images_summary">Die neueste Version aller Senderbilder herunterladen.</string>
     <string name="pref_update_station_images_title">Senderbilder aktualisieren</string>
+    <string name="pref_test_notification_title">Test-Benachrichtigung</string>
+    <string name="pref_test_notification_summary">Testen, ob das Benachrichtigungssystem funktioniert.</string>
     <!-- Sample Text -->
     <!-- App Shortcuts -->
     <string name="shortcut_last_station_disabled_message">Verknüpfung für Wiedergabe des letzten Senders deaktiviert.</string>

app/src/main/res/values-el/strings.xml

@@ -86,6 +86,8 @@
     <string name="pref_theme_selection_title">Θέμα Εφαρμογής</string>
     <string name="pref_update_station_images_summary">Κατεβάστε την τελευταία έκδοση των εικόνων όλων των σταθμών.</string>
     <string name="pref_update_station_images_title">Ενημέρωση Εικόνων Σταθμών</string>
+    <string name="pref_test_notification_title">Δοκιμαστική Ειδοποίηση</string>
+    <string name="pref_test_notification_summary">Έλεγχος αν το σύστημα ειδοποιήσεων λειτουργεί.</string>
     <!-- Sample Text -->
     <!-- App Shortcuts -->
     <string name="shortcut_last_station_disabled_message">Η συντόμευση για την αναπαραγωγή του τελευταίου σταθμού έχει απενεργοποιηθεί.</string>

app/src/main/res/values-fr/strings.xml

@@ -86,6 +86,8 @@
     <string name="pref_theme_selection_title">Thème de lapplication</string>
     <string name="pref_update_station_images_summary">Télécharger la dernière version de toutes les images des stations.</string>
     <string name="pref_update_station_images_title">Mettre à jour les images des stations</string>
+    <string name="pref_test_notification_title">Notification de test</string>
+    <string name="pref_test_notification_summary">Tester si le système de notification fonctionne.</string>
     <!-- Raccourcis de l'app -->
     <string name="shortcut_last_station_disabled_message">Raccourci pour lire la dernière station désactivé.</string>
     <string name="shortcut_last_station_long_label">Lire la dernière station</string>

app/src/main/res/values-ja/strings.xml

@@ -86,6 +86,8 @@
     <string name="pref_theme_selection_title">アプリテーマ</string>
     <string name="pref_update_station_images_summary">すべての局画像を最新に更新します。</string>
     <string name="pref_update_station_images_title">局画像を更新</string>
+    <string name="pref_test_notification_title">テスト通知</string>
+    <string name="pref_test_notification_summary">通知システムが動作するかテストします。</string>
     <!-- ショートカット -->
     <string name="shortcut_last_station_disabled_message">最後に再生した局のショートカットは無効になっています。</string>
     <string name="shortcut_last_station_long_label">最後の局を再生</string>

app/src/main/res/values-nl/strings.xml

@@ -86,6 +86,8 @@
     <string name="pref_theme_selection_title">App Thema</string>
     <string name="pref_update_station_images_summary">Download de laatste versie van alle zenderafbeeldingen.</string>
     <string name="pref_update_station_images_title">Update Zenderafbeeldingen</string>
+    <string name="pref_test_notification_title">Testmelding</string>
+    <string name="pref_test_notification_summary">Test of het meldingsysteem werkt.</string>
     <!-- Sample Text -->
     <!-- App Shortcuts -->
     <string name="shortcut_last_station_disabled_message">Snelkoppeling voor het afspelen van de laatste zender uitgeschakeld.</string>

app/src/main/res/values-pl/strings.xml

@@ -86,6 +86,8 @@
     <string name="pref_theme_selection_title">Motyw aplikacji</string>
     <string name="pref_update_station_images_summary">Pobierz najnowszą wersję wszystkich obrazów stacji w swojej kolekcji.</string>
     <string name="pref_update_station_images_title">Aktualizuj zdjęcia stacji</string>
+    <string name="pref_test_notification_title">Testowe powiadomienie</string>
+    <string name="pref_test_notification_summary">Sprawdź, czy system powiadomień działa.</string>
     <!-- Sample Text -->
     <!-- App Shortcuts -->
     <string name="shortcut_last_station_disabled_message">Skrót do odtwarzania ostatniej stacji jest wyłączony.</string>

app/src/main/res/values-ru/strings.xml

@@ -86,6 +86,8 @@
     <string name="pref_theme_selection_title">Тема приложения</string>
     <string name="pref_update_station_images_summary">Скачать последнюю версию всех изображений станций.</string>
     <string name="pref_update_station_images_title">Обновить изображения станций</string>
+    <string name="pref_test_notification_title">Тест уведомления</string>
+    <string name="pref_test_notification_summary">Проверить, работает ли система уведомлений.</string>
     <!-- Sample Text -->
     <!-- App Shortcuts -->
     <string name="shortcut_last_station_disabled_message">Ярлык для воспроизведения последней станции отключён.</string>

app/src/main/res/values-uk/strings.xml

@@ -86,6 +86,8 @@
     <string name="pref_theme_selection_title">Тема застосунку</string>
     <string name="pref_update_station_images_summary">Завантажити останню версію всіх зображень станцій.</string>
     <string name="pref_update_station_images_title">Оновити зображення станцій</string>
+    <string name="pref_test_notification_title">Тестове сповіщення</string>
+    <string name="pref_test_notification_summary">Перевірити, чи працює система сповіщень.</string>
     <!-- Sample Text -->
     <!-- App Shortcuts -->
     <string name="shortcut_last_station_disabled_message">Ярлик для відтворення останньої станції вимкнено.</string>

app/src/main/res/values/strings.xml

@@ -146,6 +146,8 @@
     <string name="pref_theme_selection_title">App Theme</string>
     <string name="pref_update_station_images_summary">Download latest version of all station images.</string>
     <string name="pref_update_station_images_title">Update Station Images</string>
+    <string name="pref_test_notification_title">Test Notification</string>
+    <string name="pref_test_notification_summary">Test whether the notification system works.</string>
 
     <!-- Sample Text -->
     <string name="sample_text_sleep_timer_remaining_time" translatable="false">00:00</string>