fix(subtitles): address CodeRabbit review

- 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).

components/video-player/controls/contexts/VideoContext.tsx

@@ -198,7 +198,9 @@ export const VideoProvider: React.FC<{ children: ReactNode }> = ({
         // track list (same as online) — robust to the transcoded file's track
         // structure differing from the original MediaStreams. Order matches web.
         for (const sub of [...allSubs].sort(compareTracksForMenu)) {
-          if (sub.IsTextSubtitleStream) {
+          // Treat missing IsTextSubtitleStream as text (image-based only when
+          // explicitly false — matches isImageBasedSubtitle).
+          if (!isImageBasedSubtitle(sub)) {
             subs.push({
               name: sub.DisplayTitle || "Unknown",
               index: sub.Index ?? -1,