Several small bug fixes (#717)

## Description
- Fixes a copy-paste error where checking if Seerr support 4K for TV
accidently used the movie 4K value
- Always show the loading indicator while waiting for playback to begin
- This has the side effect of fixing MPV playback not starting until the
UI changes (recomposes). That's a hacky fix, but should work while I try
to figure out the real cause

### Related issues
Fixes #715

app/src/main/java/com/github/damontecres/wholphin/ui/detail/discover/DiscoverSeriesViewModel.kt

@@ -67,7 +67,7 @@ class DiscoverSeriesViewModel
         val canCancelRequest = MutableStateFlow(false)
 
         val userConfig = seerrServerRepository.current.map { it?.config }
-        val request4kEnabled = seerrServerRepository.current.map { it?.request4kMovieEnabled ?: false }
+        val request4kEnabled = seerrServerRepository.current.map { it?.request4kTvEnabled ?: false }
 
         init {
             init()

app/src/main/java/com/github/damontecres/wholphin/ui/playback/PlaybackPage.kt

@@ -302,15 +302,12 @@ fun PlaybackPage(
                         modifier = scaledModifier,
                     )
                     if (presentationState.coverSurface) {
-                        val isLoading by rememberPlayerLoadingState(player)
                         Box(
                             Modifier
                                 .matchParentSize()
                                 .background(Color.Black),
                         ) {
-                            if (isLoading) {
+                            LoadingPage(focusEnabled = false)
-                                LoadingPage(focusEnabled = false)
-                            }
                         }
                     }