- Unify external detection: isExternalSubtitle drops the bare-DeliveryUrl case
(an Hls-delivered sub has a DeliveryUrl but isn't sub-add-ed) so sorting,
loading and resolution agree; compareTracksForMenu now uses it.
- applyMpvSubtitleSelection wraps player calls in try/catch — fire-and-forget
call sites no longer risk unhandled rejections.
- VideoContext offline-transcoded branch: treat missing IsTextSubtitleStream as
text (use !isImageBasedSubtitle), matching the shared helper.
- ItemContent.tv refreshSubtitleTracks: apply compareTracksForMenu like the
initial list.
- Tests: use the @/ alias; rework the embedded cases to actually exercise
identity (reversed player order) and the ordinal fallback (same-language,
no title).
resolveSubtitleTrack matches a Jellyfin subtitle against the player's real
track list (external by external-filename, embedded by language/title) instead
of positional counting, which mis-selects when externals/embedded are reordered
or the server hides embedded subs. applyMpvSubtitleSelection is the shared entry
point (reusable for the cast backend). compareTracksForMenu mirrors web's
itemHelper.sortTracks. Drops dead getMpvSubtitleId/isSubtitleInMpv. 14 unit tests.
