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_de.arb

@@ -1800,6 +1800,11 @@
   "watchProgressLearned": "Gelernt · {days, plural, =0{heute wieder} =1{morgen wieder} other{in {days} Tagen wieder}}",
   "watchJisho": "Auf Jisho nachschlagen",
   "watchWider": "Längere Wörter hier",
+  "watchWordsTitleSong": "Wörter in diesem Lied",
+  "watchStudyWordsSong": "Die Wörter dieses Lieds lernen",
+  "watchStudyNothingSong": "Das Lernset enthält noch keins der Wörter dieses Lieds",
+  "watchNoLyrics": "Dieses Lied hat keinen Liedtext, es gibt nichts nachzuschlagen.",
+  "jellyfinNoLyrics": "Kein Liedtext",
   "watchStudy": "Lernen",
   "watchStudyWords": "Die Wörter dieses Videos lernen",
   "watchStudyNothing": "Das Lernset enthält noch keins der Wörter dieses Videos",