Add support for Android TV and update dependencies

*   Implement initial Android TV support, including `LEANBACK_LAUNCHER` intent filter, hardware feature declarations, and television-specific layouts for the player, search results, and dialogs.
*   Add a splash/loading screen for the TV interface and a dedicated `SplashTheme`.
*   Improve DPAD navigation by adding `OnKeyListener` for station cards and allowing focus on internal elements.
*   Update `LayoutHolder` and `PlayerFragment` to handle TV layouts and add previous/next station navigation buttons.
*   Adjust `PreferencesHelper` to disable station editing by default on TV devices.
*   Update `androidx.media3` to v1.10.0, `work-runtime-ktx` to v2.11.2, and add `androidx.leanback` dependency.
*   Bump `versionCode` to 144 and `versionName` to 14.4.
*   Refactor `PlayerService` to simplify sleep timer cancellation logic.
*   Remove stale copyright headers and license comments from several Kotlin files.

app/build.gradle

@@ -19,8 +19,8 @@ android {
         applicationId 'com.michatec.radio'
         minSdk 28
         targetSdk 36
-        versionCode 143
-        versionName '14.3'
+        versionCode 144
+        versionName '14.4'
         resourceConfigurations += ['en', 'de', 'el', 'nl', 'pl', 'ru','uk', 'ja', 'da', 'fr']
     }
 
@@ -71,6 +71,7 @@ dependencies {
     implementation libs.navigation.fragment.ktx
     implementation libs.navigation.ui.ktx
     implementation libs.work.runtime.ktx
+    implementation libs.leanback
 
     implementation libs.freedroidwarn