feat(mini-player): optional preload toggle for Linux + macOS

Adds a "Preload mini player" toggle in Settings → General → App behaviour
(off by default). When enabled, the mini webview is built hidden at app
start so the first open is instant, matching the Windows experience.
Costs one extra WebKit process running in the background (~50–100 MB).

Windows already pre-creates the mini unconditionally as a hang workaround
(commit 71fbc717); the toggle is hidden there and the invoke is skipped,
so that platform is untouched.

- authStore: new `preloadMiniPlayer: boolean` (default false) + setter.
- lib.rs: new `preload_mini_player` command; idempotent, no-op when the
  window already exists. Registered in the invoke handler.
- App.tsx: main window invokes `preload_mini_player` when the toggle is
  on and the platform is not Windows.
- Settings.tsx: toggle row under "Minimize to Tray", gated with
  `!IS_WINDOWS` so Windows users don't see it.
- i18n: `preloadMiniPlayer` + `preloadMiniPlayerDesc` added to all 8
  locales (en, de, es, fr, nb, nl, ru, zh).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/locales/de.ts

@@ -553,6 +553,8 @@ export const deTranslation = {
     showTrayIconDesc: 'Psysonic-Icon im System-Tray / in der Menüleiste anzeigen.',
     minimizeToTray: 'Im Tray minimieren',
     minimizeToTrayDesc: 'Beim Schließen des Fensters läuft Psysonic weiter im System-Tray statt zu beenden.',
+    preloadMiniPlayer: 'Mini-Player vorladen',
+    preloadMiniPlayerDesc: 'Baut das Mini-Player-Fenster beim App-Start im Hintergrund auf, damit es beim ersten Öffnen sofort Inhalt zeigt. Kostet etwas mehr RAM.',
     discordRichPresence: 'Discord Rich Presence',
     discordRichPresenceDesc: 'Zeigt den aktuell gespielten Titel im Discord-Profil an. Discord muss dafür geöffnet sein.',
     useCustomTitlebar: 'Eigene Titelleiste',

src/locales/en.ts

@@ -555,6 +555,8 @@ export const enTranslation = {
     showTrayIconDesc: 'Display the Psysonic icon in the system notification area / menu bar.',
     minimizeToTray: 'Minimize to Tray',
     minimizeToTrayDesc: 'When closing the window, keep Psysonic running in the system tray instead of quitting.',
+    preloadMiniPlayer: 'Preload mini player',
+    preloadMiniPlayerDesc: 'Build the mini player window in the background at app start so it shows content instantly on first open. Uses a little extra memory.',
     discordRichPresence: 'Discord Rich Presence',
     discordRichPresenceDesc: 'Show the currently playing track on your Discord profile. Requires Discord to be running.',
     useCustomTitlebar: 'Custom title bar',

src/locales/es.ts

@@ -546,6 +546,8 @@ export const esTranslation = {
     showTrayIconDesc: 'Muestra el icono de Psysonic en el área de notificación / barra de menú.',
     minimizeToTray: 'Minimizar a Bandeja',
     minimizeToTrayDesc: 'Al cerrar la ventana, mantener Psysonic ejecutándose en la bandeja del sistema en lugar de salir.',
+    preloadMiniPlayer: 'Precargar mini reproductor',
+    preloadMiniPlayerDesc: 'Crea la ventana del mini reproductor en segundo plano al iniciar la aplicación para que muestre contenido al instante la primera vez que se abre. Consume un poco más de memoria.',
     discordRichPresence: 'Discord Rich Presence',
     discordRichPresenceDesc: 'Muestra la pista actual en tu perfil de Discord. Requiere que Discord esté ejecutándose.',
     useCustomTitlebar: 'Barra de título personalizada',

src/locales/fr.ts

@@ -543,6 +543,8 @@ export const frTranslation = {
     showTrayIconDesc: 'Affiche l\'icône Psysonic dans la zone de notification / barre des menus.',
     minimizeToTray: 'Réduire dans la barre système',
     minimizeToTrayDesc: 'Lors de la fermeture, Psysonic continue de fonctionner dans la barre système au lieu de se fermer.',
+    preloadMiniPlayer: 'Précharger le mini-lecteur',
+    preloadMiniPlayerDesc: 'Construit la fenêtre du mini-lecteur en arrière-plan au démarrage de l\'application afin qu\'elle affiche son contenu instantanément à la première ouverture. Utilise un peu plus de mémoire.',
     linuxWebkitSmoothScroll: 'Molette fluide (Linux)',
     linuxWebkitSmoothScrollDesc: 'Activé : inertie. Désactivé : pas à la ligne, style GTK.',
     discordRichPresence: 'Discord Rich Presence',

src/locales/nb.ts

@@ -542,6 +542,8 @@ export const nbTranslation = {
     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',
     minimizeToTrayDesc: 'Når vinduet lukkes, vil Psysonic bli kjørende i oppgavelinjen fremfor å bli avsluttet.',
+    preloadMiniPlayer: 'Forhåndslast miniavspiller',
+    preloadMiniPlayerDesc: 'Bygger miniavspiller-vinduet i bakgrunnen ved appstart slik at det viser innhold umiddelbart ved første åpning. Bruker litt mer minne.',
     linuxWebkitSmoothScroll: 'Mykt musehjul (Linux)',
     linuxWebkitSmoothScrollDesc: 'På: treg rull med etterslep. Av: trinnvis som i GTK.',
     discordRichPresence: 'Discord Rich Presence',

src/locales/nl.ts

@@ -542,6 +542,8 @@ export const nlTranslation = {
     showTrayIconDesc: 'Toont het Psysonic-pictogram in het systeemvak / de menubalk.',
     minimizeToTray: 'Minimaliseren naar systeemvak',
     minimizeToTrayDesc: 'Bij het sluiten van het venster blijft Psysonic actief in het systeemvak in plaats van af te sluiten.',
+    preloadMiniPlayer: 'Mini-speler vooraf laden',
+    preloadMiniPlayerDesc: 'Bouwt het venster van de mini-speler op de achtergrond bij het opstarten van de app, zodat het bij de eerste opening direct inhoud toont. Gebruikt iets meer geheugen.',
     linuxWebkitSmoothScroll: 'Vloeiend muiswiel (Linux)',
     linuxWebkitSmoothScrollDesc: 'Aan: traag naloop. Uit: regel voor regel, GTK-stijl.',
     discordRichPresence: 'Discord Rich Presence',

src/locales/ru.ts

@@ -563,6 +563,8 @@ export const ruTranslation = {
     showTrayIconDesc: 'Показывать Psysonic в области уведомлений / строке меню.',
     minimizeToTray: 'Сворачивать в трей',
     minimizeToTrayDesc: 'При закрытии окна не выходить из приложения, а оставаться в трее.',
+    preloadMiniPlayer: 'Предзагрузка мини-плеера',
+    preloadMiniPlayerDesc: 'Создаёт окно мини-плеера в фоне при запуске приложения, чтобы при первом открытии содержимое отображалось мгновенно. Использует немного больше памяти.',
     useCustomTitlebar: 'Своя строка заголовка',
     useCustomTitlebarDesc:
       'Заменить системную строку заголовка встроенной, в стиле темы приложения. Отключите, чтобы использовать родную строку GNOME/GTK и т.д.',

src/locales/zh.ts

@@ -538,6 +538,8 @@ export const zhTranslation = {
     showTrayIconDesc: '在系统通知区域 / 菜单栏显示 Psysonic 图标。',
     minimizeToTray: '最小化到托盘',
     minimizeToTrayDesc: '关闭窗口时，Psysonic 将继续在系统托盘中运行，而不是退出。',
+    preloadMiniPlayer: '预加载迷你播放器',
+    preloadMiniPlayerDesc: '在应用启动时于后台构建迷你播放器窗口，使其首次打开即可立即显示内容。会占用少量额外内存。',
     linuxWebkitSmoothScroll: '滚轮平滑（Linux）',
     linuxWebkitSmoothScrollDesc: '开：惯性滚动。关：逐行，类似 GTK。',
     discordRichPresence: 'Discord Rich Presence',