feat(jellyfin): an episode's own tag, and studying an episode's words

A word added from an episode gets the show's tag and the episode's own ("あかね噺 S1 E1"), hidden on cards. The words panel's Study button studies the studyset's cards of the video's words, on their schedules or crammed (each once): it pauses the video and first gives the episode's tag to the cards of its words the studyset held before, then opens the session on that tag. A study focus can now ask for cramming.

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",
+  "watchStudy": "Lernen",
+  "watchStudyWords": "Die Wörter dieses Videos lernen",
+  "watchStudyNothing": "Das Lernset enthält noch keins der Wörter dieses Videos",
+  "watchStudyScheduled": "Lernen, nach Plan",
+  "watchStudyCram": "Pauken, jedes einmal",
   "watchFilter": "Wörter filtern",
   "watchFilterFresh": "Neue Wörter",
   "watchFilterHeld": "Wörter im Lernset",