House policy: user actions must report failure. Added onError to:
- ChannelPage block + unsubscribe → notifyYouTubeActionError (a 403 = missing YT
scope shows the connect message; else the translated fallback);
- SettingsPanel PlexWatchSync toggle + reimport → a plain error notify (these are
Plex, not YouTube, so notifyYouTubeActionError's "connect YouTube" would mislead);
- DownloadCenter job action (pause/resume/cancel/delete) → a plain error notify.
New keys (HU+EN): channels.notify.blockFailed, settings.plexSync.failed,
downloads.actionFailed.