feat(audio): bit-perfect hi-res playback + underrun hardening (opt-in alpha)

Safe mode (default): all audio outputs at 44.1 kHz, rodio resamples
internally. Maximum stability out of the box.

Hi-Res mode (alpha toggle): stream opens at the file's native sample rate
(e.g. 88.2/96/192 kHz) for bit-perfect output.

Rust (audio.rs):
- open_stream_for_rate(): CPAL queries device supported configs, finds
  exact rate match or falls back to highest available / device default.
- create_engine() thread: ThreadPriority::Max (silently ignored without
  CAP_SYS_NICE), loop handles rate-switch requests, PIPEWIRE_LATENCY
  scales with rate (8192 frames for >48 kHz ≈ 93 ms quantum), keeps
  PULSE_LATENCY_MSEC in sync.
- audio_play(): hi_res_enabled param gates effective_rate (44100 vs
  native); stream re-opens only when needed; 150 ms PipeWire settle +
  500 ms sink pre-fill (pause→append→sleep→play) for hi-res tracks.
- audio_chain_preload(): hi_res_enabled param; rate-mismatch bail skipped
  in safe mode so gapless chains always work at 44.1 kHz.
- SizedDecoder MSS buffer: 4 MB (was 512 KB) to reduce Symphonia read
  overhead on high-bitrate hi-res files.
- thread-priority crate added to Cargo.toml.

Frontend:
- authStore: enableHiRes (bool, default false) + setEnableHiRes.
- playerStore: hiResEnabled passed to all audio_play /
  audio_chain_preload invoke calls.
- Settings → Audio tab: "Native Hi-Res Playback" toggle with Alpha
  badge and stability warning, i18n for all 7 languages.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/locales/de.ts

@@ -430,6 +430,9 @@ export const deTranslation = {
     hotCacheDebounceImmediate: 'Sofort',
     hotCacheDebounceSeconds: '{{n}} s',
     hotCacheClearBtn: 'Hot-Cache leeren',
+    hiResTitle: 'Native Hi-Res-Wiedergabe',
+    hiResEnabled: 'Native Hi-Res-Wiedergabe aktivieren',
+    hiResDesc: "Standardmäßig wird auf 44,1 kHz begrenzt (maximale Stabilität). Nur aktivieren, wenn Hardware und Netzwerk zuverlässig hohe Abtastraten (88,2 kHz+) unterstützen.",
     showArtistImages: 'Künstlerbilder anzeigen',
     showArtistImagesDesc: 'Lädt und zeigt Künstlerbilder in der Künstlerübersicht. Standardmäßig deaktiviert, um Server-I/O und Netzwerklast bei großen Bibliotheken zu reduzieren.',
     showTrayIcon: 'Tray-Icon anzeigen',

src/locales/en.ts

@@ -430,6 +430,9 @@ export const enTranslation = {
     hotCacheDebounceImmediate: 'Immediate',
     hotCacheDebounceSeconds: '{{n}} s',
     hotCacheClearBtn: 'Clear hot cache',
+    hiResTitle: 'Native Hi-Res Playback',
+    hiResEnabled: 'Enable native hi-res playback',
+    hiResDesc: "Forces 44.1 kHz output by default for maximum stability. Enable only if your hardware and network reliably support high sample rates (88.2 kHz+).",
     showArtistImages: 'Show Artist Images',
     showArtistImagesDesc: 'Load and display artist images in the Artists overview. Disabled by default to reduce server disk I/O and network load on large libraries.',
     showTrayIcon: 'Show Tray Icon',

src/locales/fr.ts

@@ -430,6 +430,9 @@ export const frTranslation = {
     hotCacheDebounceImmediate: 'Immédiat',
     hotCacheDebounceSeconds: '{{n}} s',
     hotCacheClearBtn: 'Vider le cache à chaud',
+    hiResTitle: 'Lecture haute résolution native',
+    hiResEnabled: 'Activer la lecture haute résolution native',
+    hiResDesc: "Force une sortie à 44,1 kHz par défaut pour une stabilité maximale. N'activer que si le matériel et le réseau prennent en charge les hautes fréquences d'échantillonnage (88,2 kHz+).",
     showArtistImages: 'Afficher les images d\'artistes',
     showArtistImagesDesc: 'Charge et affiche les images d\'artistes dans la vue d\'ensemble. Désactivé par défaut pour réduire les E/S disque serveur et la charge réseau sur les grandes bibliothèques.',
     showTrayIcon: 'Afficher l\'icône dans la barre système',

src/locales/nb.ts

@@ -431,6 +431,9 @@ export const nbTranslation = {
     hotCacheDebounceImmediate: 'Umiddelbart',
     hotCacheDebounceSeconds: '{{n}} sek',
     hotCacheClearBtn: 'Tøm varm buffer',
+    hiResTitle: 'Innebygd hi-res-avspilling',
+    hiResEnabled: 'Aktiver innebygd hi-res-avspilling',
+    hiResDesc: "Begrenser utdata til 44,1 kHz som standard for maksimal stabilitet. Aktiver kun hvis maskinvare og nettverk støtter høye samplingsrater (88,2 kHz+) pålitelig.",
     showArtistImages: 'Vis artistbilder',
     showArtistImagesDesc: 'Last inn og vis artistbilder i artistoversikten. Denne er deaktivert som standard, for å redusere disk-I/O og nettverksbelastningen på store biblioteker.',
     minimizeToTray: 'Minimer til oppgavelinjen',

src/locales/nl.ts

@@ -430,6 +430,9 @@ export const nlTranslation = {
     hotCacheDebounceImmediate: 'Direct',
     hotCacheDebounceSeconds: '{{n}} s',
     hotCacheClearBtn: 'Warme cache wissen',
+    hiResTitle: 'Natieve hi-res-weergave',
+    hiResEnabled: 'Natieve hi-res-weergave inschakelen',
+    hiResDesc: "Beperkt de uitvoer standaard tot 44,1 kHz voor maximale stabiliteit. Alleen inschakelen als hardware en netwerk hoge samplerates (88,2 kHz+) ondersteunen.",
     showArtistImages: 'Artiestafbeeldingen weergeven',
     showArtistImagesDesc: 'Laadt en toont artiestafbeeldingen in het artiestenoverzicht. Standaard uitgeschakeld om server-I/O en netwerkbelasting bij grote bibliotheken te beperken.',
     showTrayIcon: 'Tray-pictogram weergeven',

src/locales/ru.ts

@@ -447,6 +447,9 @@ export const ruTranslation = {
     hotCacheDebounceImmediate: 'Сразу',
     hotCacheDebounceSeconds: '{{n}} с',
     hotCacheClearBtn: 'Очистить горячий кэш',
+    hiResTitle: 'Нативное воспроизведение Hi-Res',
+    hiResEnabled: 'Включить нативное Hi-Res воспроизведение',
+    hiResDesc: "По умолчанию ограничивает вывод до 44,1 кГц для максимальной стабильности. Включайте только если оборудование и сеть надёжно поддерживают высокие частоты (88,2 кГц+).",
     showArtistImages: 'Фото исполнителей',
     showArtistImagesDesc:
       'Показывать обложки в разделе «Исполнители». По умолчанию выключено — меньше нагрузки на диск и сеть.',

src/locales/zh.ts

@@ -426,6 +426,9 @@ export const zhTranslation = {
     hotCacheDebounceImmediate: '立即',
     hotCacheDebounceSeconds: '{{n}} 秒',
     hotCacheClearBtn: '清空热缓存',
+    hiResTitle: '原生高清晰度播放',
+    hiResEnabled: '启用原生高清晰度播放',
+    hiResDesc: "默认强制 44.1 kHz 输出以获得最大稳定性。仅在硬件和网络可靠支持高采样率（88.2 kHz+）时启用。",
     showArtistImages: '显示艺术家图片',
     showArtistImagesDesc: '在艺术家概览中加载并显示艺术家图片。默认关闭以减少大型音乐库的服务器磁盘I/O和网络负载。',
     showTrayIcon: '显示托盘图标',