Player overlay: real transport buttons (pause/stop/audio), OK opens controls

OK now opens the overlay like every TV player; its buttons are ordinary
focusable pills (play/pause, stop, audio-track cycle). Back closes the
overlay first, then stops. Auto-hide timer restarts on any interaction.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/build.gradle.kts

@@ -12,8 +12,8 @@ android {
         applicationId = "dev.castarr.tv"
         minSdk = 26
         targetSdk = 35
-        versionCode = 8
-        versionName = "0.4.0"
+        versionCode = 9
+        versionName = "0.4.1"
     }
 
     // Release signing from environment (see ~/.keys/castarr-release.env on the