feat(settings): add UI defaults for audio/subtitle language and subtitle type

[Copilot]

Users could only set preferred audio/subtitle languages through advanced VLC arguments or per-playback track selection. This change adds first-class Settings UI for these preferences and applies them in app playback logic (not LibVLC startup arguments).

• Settings surface (Player section)

  • Added new preferences:
    • Preferred audio language
    • Preferred subtitle language
    • Preferred subtitle type (Any, Full subtitles, Signs / songs)
  • Added corresponding en-US resource strings for labels/descriptions/options.

• Persisted settings model

  • Extended ISettingsService/SettingsService with:
    • PersistentAudioLanguage
    • PersistentSubtitleTypePreference
  • Reused existing PersistentSubtitleLanguage for subtitle language selection from Settings.

• Playback selection logic (application-side)

  • On media item change, applies preferred audio language against available audio tracks.
  • Subtitle language matching now supports subtitle type prioritization:
    • Any: first language match
    • Full: prefer non-signs/song tracks
    • Signs / songs: prefer signs/song/lyric/forced-labeled tracks
  • Track selections made from the in-player picker update persisted language preferences.

• Example (selection behavior)

int? selectedIndex = subtitleTypePreference switch
{
    2 => signSongMatch ?? firstMatch,
    1 => fullMatch ?? firstMatch,
    _ => firstMatch
};

if (selectedIndex is int value)
{
    subtitleTrackList.SelectedIndex = value;
}

• • User-provided screenshot URL was reviewed but does not show these newly added settings controls, so it is not included as UI evidence for this PR.

[United600]

After a brief review, I wasn't particularly impressed.

I wouldn't make the default audio or subtitle language that prominent (if at all). Each setting fits better as its own card within the Advanced expander.

And about the subtitle behavior, I really dislike how it's implemented. It makes more sense as an enum, and the strings/options need a thorough rewrite. It's far too English and anime‑centric, and it would even fail one of the examples in #837.
SDH and Forced tracks should be included in the supported set of behaviors.