feat(jellyfin): songs and their lyrics, read as subtitles are

A music library's artists and albums open as shows and seasons do, and
can be tied to a studyset. A song plays as sound alone (`/Audio/{id}/
stream`, as stored) with its lyrics as Jellyfin keeps them (`/Audio/{id}/
Lyrics`: an LRC file beside it, or its tags), cut into the dictionary's
words as a video's subtitles are, with no translation. Timed lyrics
follow the song: the line sung large and bright among the others faded,
scrolled to as it comes, a line tapped played from its start; untimed
ones show whole. A song without lyrics shows greyed and doesn't open
(`HasLyrics`), as there is nothing in it to read. Its cover stands where
the picture would, glowing as a video does, and its words are tagged
with the artist, shown, and "artist · title", hidden.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/lib/l10n/app_localizations_de.dart

@@ -6691,6 +6691,23 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get watchWider => 'Längere Wörter hier';
 
+  @override
+  String get watchWordsTitleSong => 'Wörter in diesem Lied';
+
+  @override
+  String get watchStudyWordsSong => 'Die Wörter dieses Lieds lernen';
+
+  @override
+  String get watchStudyNothingSong =>
+      'Das Lernset enthält noch keins der Wörter dieses Lieds';
+
+  @override
+  String get watchNoLyrics =>
+      'Dieses Lied hat keinen Liedtext, es gibt nichts nachzuschlagen.';
+
+  @override
+  String get jellyfinNoLyrics => 'Kein Liedtext';
+
   @override
   String get watchStudy => 'Lernen';