fix: address copilot review comments on playlist season PR

- Gate PlaylistIndex numbering on having a real playlist id so Unsorted
  videos get IndexNumber = null instead of 0, matching the enum docs
  and config UI text.
- Remove unused using Microsoft.Extensions.Logging from Video.cs.
- Stop catching OperationCanceledException in PlaylistCache.RefreshAsync
  and GetPlaylistSortDateAsync so cancellation propagates instead of
  silently falling back to upload year grouping.

Note: AI Generated Commit

Jellyfin.Plugin.TubeArchivistMetadata/TubeArchivist/PlaylistCache.cs

@@ -199,7 +199,7 @@ namespace Jellyfin.Plugin.TubeArchivistMetadata.TubeArchivist
             {
                 playlists = await taApi.GetPlaylists().ConfigureAwait(false);
             }
-            catch (Exception ex) when (ex is HttpRequestException or OperationCanceledException or JsonException)
+            catch (Exception ex) when (ex is HttpRequestException or JsonException)
             {
                 // Failure policy: keep whatever is cached and let callers fall back to upload year
                 // grouping. A partial migration is worse than no migration.
@@ -443,7 +443,7 @@ namespace Jellyfin.Plugin.TubeArchivistMetadata.TubeArchivist
                     return video.Published;
                 }
             }
-            catch (Exception ex) when (ex is HttpRequestException or OperationCanceledException or JsonException)
+            catch (Exception ex) when (ex is HttpRequestException or JsonException)
             {
                 _logger.LogDebug(ex, "Could not resolve a sort date for playlist {PlaylistId}.", playlist.Id);
             }

Jellyfin.Plugin.TubeArchivistMetadata/TubeArchivist/Video/Video.cs

@@ -9,7 +9,6 @@ using MediaBrowser.Controller.Entities;
 using MediaBrowser.Controller.Entities.TV;
 using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.Providers;
-using Microsoft.Extensions.Logging;
 using Newtonsoft.Json;
 
 namespace Jellyfin.Plugin.TubeArchivistMetadata.TubeArchivist
@@ -153,7 +152,7 @@ namespace Jellyfin.Plugin.TubeArchivistMetadata.TubeArchivist
                 IndexNumber = Plugin.Instance?.Configuration?.EpisodeNumberingScheme switch
                 {
                     NumberingScheme.YYYYMMDD => (Published.Year * 10000) + (Published.Month * 100) + Published.Day,
-                    NumberingScheme.PlaylistIndex => playlistAssignment?.Index,
+                    NumberingScheme.PlaylistIndex => !string.IsNullOrEmpty(playlistAssignment?.PlaylistId) ? playlistAssignment?.Index : null,
                     _ => null
                 },
                 SeriesName = Channel.Name,