feat(meditate): the instance's library in the app: Explore, its player, courses, keeping offline

Explore shows the instance's library below Meditate's practices, where it
has one: its courses and items by category (Meditate's eleven, named in
English and German, and the operator's own) and by the same search; an
instance without one shows nothing more. An item's page: its recordings
to choose, Play, a favourite (kept in the sealed settings under
library/<id>), keeping it on the device and removing it, and for a sound,
a silent sitting with it looped; its credit and licence. The player
plays, pauses and seeks; played to its end it is kept as a sitting, and
as its course's lesson done (lesson_done, sealed and synced). Settings
lists the library's credits beside About; Today shows its favourites.

The last catalogue is kept in the person's folder for offline; files are
fetched with the catalogue's access, asked for again shortly before it
ends. ADR 0038, D16.

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

apps/meditate/halkyon_meditate_flutter/lib/l10n/app_de.arb

@@ -171,5 +171,41 @@
   "dreamStopDictating": "Diktat beenden",
   "dreamListening": "Ich höre zu …",
   "dreamSpeechUnavailable": "Dieses Gerät kann gerade nicht zuhören. Darf die App das Mikrofon nutzen?",
-  "todayDreamSpeak": "Erzählen"
+  "todayDreamSpeak": "Erzählen",
+  "exploreLibrary": "Von {server}",
+  "libraryCourses": "Kurse",
+  "libraryCourse": "Kurs",
+  "libraryCategoryMeditation": "Meditation",
+  "libraryCategorySleepStory": "Einschlafgeschichten",
+  "libraryCategorySound": "Klänge",
+  "libraryCategoryMovement": "Bewegung",
+  "libraryCategoryAutogenicTraining": "Autogenes Training",
+  "libraryCategoryProgressiveMuscleRelaxation": "Progressive Muskelentspannung",
+  "libraryCategoryRoutine": "Routinen",
+  "libraryCategoryDreamJourney": "Traumreisen",
+  "libraryCategoryKnowledge": "Wissen",
+  "libraryCategoryMorningStory": "Morgengeschichten",
+  "libraryCategoryOther": "Anderes",
+  "libraryLessons": "{count, plural, =1{1 Lektion} other{{count} Lektionen}}",
+  "libraryLessonsDone": "{done} von {count} erledigt",
+  "libraryLessonDone": "Erledigt",
+  "libraryWith": "Mit {speaker}",
+  "libraryPlay": "Abspielen",
+  "libraryPause": "Pause",
+  "libraryResume": "Weiter",
+  "libraryStop": "Beenden",
+  "libraryRecording": "Aufnahme",
+  "libraryKeep": "Auf dem Gerät behalten",
+  "libraryKeeping": "Wird geladen …",
+  "libraryKept": "Auf dem Gerät",
+  "libraryRemove": "Vom Gerät entfernen",
+  "libraryKeepFailed": "Das ließ sich nicht laden. Versuch es wieder, wenn du online bist.",
+  "libraryPlayFailed": "Das lässt sich gerade nicht abspielen. Bist du online?",
+  "librarySitWithSound": "Mit diesem Klang still sitzen",
+  "libraryCredit": "Nachweis",
+  "libraryLicence": "Lizenz",
+  "libraryCredits": "Nachweise der Bibliothek",
+  "libraryCreditsIntro": "Was die Bibliothek von {server} bietet, wem es jeweils zu verdanken ist und unter welcher Lizenz.",
+  "libraryGone": "Das ist nicht mehr in der Bibliothek.",
+  "libraryFromLibrary": "Aus der Bibliothek"
 }