fix(sheets): size sheets to their content instead of 75% of the window

Sheets rendered at the host's maximum height regardless of content, so a
one-item player queue or a two-track picker filled ~75% of a desktop window
with empty space.

BottomSheetPageScaffold now always lays out Column(mainAxisSize: .min) plus
Flexible(child:), and each sheet body shrink-wraps its own scrollable. The
scaffold's shrinkWrap flag is gone: its old true branch put the child on an
unbounded axis, where an over-tall list overflowed instead of clamping and
scrolling. Measured on a 1600x1000 window, the chapter sheet goes from 750px
to 118px for one chapter and the two-column track sheet from 750px to 154px
for one audio and one subtitle track, both still clamping at the cap.

Add SheetSplitColumns for the three side-by-side sheet layouts. A bare
VerticalDivider has no intrinsic height, so it inflated those rows to the cap
on its own; the rule now paints from a Positioned.fill that cannot size the
Stack. IntrinsicHeight is not an option because a Viewport has no intrinsics.

Because sheets are bottom-anchored, a content-driven height moves the sheet's
top edge and everything above the change point. Three surfaces opt out for
that reason and say so at the call site: SubtitleSearchSheet and its language
picker keep filling, since both refilter under an autofocused field;
FiltersBottomSheet holds the outgoing page's height through its loading
transient; and RatingBottomSheet no longer hides MAL/AniList rows
asynchronously, which used to slide live rating controls down two rows several
hundred ms after open. Wrap the shared StateMessageWidget at the filters sheet
boundary rather than editing a widget with 33 filling call sites.

The host gains an AnimatedSize keyed per sheet session so nested pushes ease
while a replacing show adopts its own height, a 720px absolute height ceiling
on desktop windows only, and a min(max(25%, 96px), 60%) drag-dismiss threshold
so short sheets neither close on a nudge nor become undismissable.

Add videoControls.noAudioDevicesAvailable so the audio output page shows a
placeholder instead of a bare header while devices load.

lib/i18n/strings_bg.g.dart

@@ -831,6 +831,7 @@ class _Translations$videoControls$bg extends Translations$videoControls$en {
 	@override String get noChaptersAvailable => 'Няма налични глави';
 	@override String get queue => 'Опашка';
 	@override String get noQueueItems => 'Няма елементи в опашката';
+	@override String get noAudioDevicesAvailable => 'Няма налични аудио устройства';
 	@override String get searchSubtitles => 'Търсене на субтитри';
 	@override String get language => 'Език';
 	@override String get noSubtitlesFound => 'Не са намерени субтитри';
@@ -3233,6 +3234,7 @@ extension on TranslationsBg {
 			'videoControls.noChaptersAvailable' => 'Няма налични глави',
 			'videoControls.queue' => 'Опашка',
 			'videoControls.noQueueItems' => 'Няма елементи в опашката',
+			'videoControls.noAudioDevicesAvailable' => 'Няма налични аудио устройства',
 			'videoControls.searchSubtitles' => 'Търсене на субтитри',
 			'videoControls.language' => 'Език',
 			'videoControls.noSubtitlesFound' => 'Не са намерени субтитри',
@@ -3618,9 +3620,9 @@ extension on TranslationsBg {
 			'explore.badge.requested' => 'Заявен',
 			'explore.badge.pendingApproval' => 'В очакване на одобрение',
 			'explore.badge.processing' => 'Обработва се',
-			'explore.badge.declined' => 'Отхвърлен',
 			_ => null,
 		} ?? switch (path) {
+			'explore.badge.declined' => 'Отхвърлен',
 			'explore.badge.requestFailed' => 'Заявката се провали',
 			'explore.badge.requested4k' => 'Заявен в 4K',
 			'explore.badge.seasonsAvailable' => ({required Object available, required Object total}) => '${available}/${total} сезона',
@@ -4132,9 +4134,9 @@ extension on TranslationsBg {
 			'performanceOverlay.dropped' => 'Пропуснати кадри',
 			'performanceOverlay.dvRpus' => 'DV RPU',
 			'performanceOverlay.dvRpuAverage' => 'Средно DV RPU',
-			'performanceOverlay.dvSampleAverage' => 'Средно DV семпл',
 			_ => null,
 		} ?? switch (path) {
+			'performanceOverlay.dvSampleAverage' => 'Средно DV семпл',
 			'performanceOverlay.maxLuma' => 'Макс. яркост',
 			'performanceOverlay.minLuma' => 'Мин. яркост',
 			'performanceOverlay.maxCll' => 'MaxCLL',