Several minor fixes (#1505)

## Description
Collecting some minor fixes together:

- Adds error handling when submitting a discover/seerr request,
previously there was no visual feedback if the request failed
- Fix MpvPlayer reporting that it was buffering forever
- Fix discover results row on regular search page not being clickable
- Fix focus loss when returning to movie details after playback advanced
enough to switch the button from Play to Resume
- Fix some focus issues when returning to the TV guide page

### Related issues
Related to #1503 for MPV
Fixes #1500
Fixes #1508
Fixes #1501

### Testing
Emulator & nvidia shield

## Screenshots
N/A

## AI or LLM usage
None

app/src/main/java/com/github/damontecres/wholphin/util/mpv/MpvPlayer.kt

@@ -628,12 +628,11 @@ class MpvPlayer(
 
             MPVProperty.PAUSED_FOR_CACHE -> {
                 Timber.v("paused-for-cache %s", value)
+                val newState = if (value) STATE_BUFFERING else STATE_READY
                 playbackState.update {
-                    it.copy(
-                        state = if (value) STATE_BUFFERING else it.state,
-                    )
+                    it.copy(state = newState)
                 }
-                notifyListeners(EVENT_PLAYBACK_STATE_CHANGED) { onPlaybackStateChanged(playbackState.load().state) }
+                notifyListeners(EVENT_PLAYBACK_STATE_CHANGED) { onPlaybackStateChanged(newState) }
             }
         }
     }
@@ -842,6 +841,7 @@ class MpvPlayer(
             )
         }
         notifyListeners(EVENT_IS_LOADING_CHANGED) { onIsLoadingChanged(true) }
+        notifyListeners(EVENT_PLAYBACK_STATE_CHANGED) { onPlaybackStateChanged(STATE_READY) }
         val url =
             media.mediaItem.localConfiguration
                 ?.uri