fix: propagate ICY metadata to MediaItem and remove unsafe stopSelf

- updateMetadata() now also updates _currentMediaItem so track info
  and artwork flow through to the notification/lockscreen via getState()
- Remove else -> stopSelf() from onStartCommand to avoid killing the
  service on internal MediaLibraryService intents

Made-with: Cursor

app/src/main/java/xyz/cottongin/radio247/service/RadioPlayerAdapter.kt

@@ -107,6 +107,10 @@ class RadioPlayerAdapter(
             .setArtworkUri(artworkUri)
             .setIsPlayable(true)
             .build()
+        _currentMediaItem = MediaItem.Builder()
+            .setMediaId(_currentMediaItem?.mediaId ?: "station:${station.id}")
+            .setMediaMetadata(_mediaMetadata)
+            .build()
         invalidateState()
     }