refactor: remove Tauri auto-updater, replace with simple GitHub-check modal

Remove tauri-plugin-updater, relaunch_after_update command, generate-update-
manifest.js, the generate-manifest CI job, and all signing/upload steps for
.sig files and latest.json. The updater plugin, its pubkey and endpoint config
in tauri.conf.json, and the updater:default capability are all gone.

Replace AppUpdater.tsx with a lightweight component that:
- Fetches https://api.github.com/repos/Psychotoxical/psysonic/releases/latest
  after a 4 s delay (no install, no download, no progress bar)
- Shows a dismissible toast with two buttons:
  GitHub → releases/latest
  Website → https://psysonic.psychotoxic.eu/#downloads

i18n: remove updaterInstall/Downloading/Installing/Download/ExperimentalHint
keys from all 7 locales; add updaterWebsite; update updaterVersion wording.

CI: remove generate-manifest job and all .sig signing/upload steps from
build-macos-windows. Also remove TAURI_SIGNING_PRIVATE_KEY env vars (no
longer needed). Release now just builds and uploads the installable binaries.

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

src/locales/de.ts

@@ -15,9 +15,6 @@ export const deTranslation = {
     help: 'Hilfe',
     expand: 'Sidebar einblenden',
     collapse: 'Sidebar ausblenden',
-    updateAvailable: 'Update verfügbar',
-    updateReady: '{{version}} ist bereit',
-    updateLink: 'Zum Release →',
     downloadingTracks: '{{n}} Tracks werden gecacht…',
     offlineLibrary: 'Offline-Bibliothek',
     genres: 'Genres',
@@ -328,12 +325,8 @@ export const deTranslation = {
     bulkRemoveFromPlaylist: 'Aus Playlist entfernen',
     bulkClear: 'Auswahl aufheben',
     updaterAvailable: 'Update verfügbar',
-    updaterVersion: 'v{{version}} ist bereit',
-    updaterInstall: 'Installieren & Neustart',
-    updaterDownloading: 'Wird geladen…',
-    updaterInstalling: 'Wird installiert…',
-    updaterDownload: 'Von GitHub herunterladen',
-    updaterExperimentalHint: 'Automatische Updates sind noch in Entwicklung',
+    updaterVersion: 'v{{version}} verfügbar',
+    updaterWebsite: 'Website',
   },
   settings: {
     title: 'Einstellungen',

src/locales/en.ts

@@ -15,9 +15,7 @@ export const enTranslation = {
     help: 'Help',
     expand: 'Expand Sidebar',
     collapse: 'Collapse Sidebar',
-    updateAvailable: 'Update available',
-    updateReady: '{{version}} is ready',
-    updateLink: 'Go to release →',
+
     downloadingTracks: 'Caching {{n}} tracks…',
     offlineLibrary: 'Offline Library',
     genres: 'Genres',
@@ -328,12 +326,8 @@ export const enTranslation = {
     bulkRemoveFromPlaylist: 'Remove from Playlist',
     bulkClear: 'Clear selection',
     updaterAvailable: 'Update available',
-    updaterVersion: 'v{{version}} is ready',
-    updaterInstall: 'Install & Restart',
-    updaterDownloading: 'Downloading…',
-    updaterInstalling: 'Installing…',
-    updaterDownload: 'Download from GitHub',
-    updaterExperimentalHint: 'Auto-update is still in development',
+    updaterVersion: 'v{{version}} is available',
+    updaterWebsite: 'Website',
   },
   settings: {
     title: 'Settings',

src/locales/fr.ts

@@ -15,9 +15,6 @@ export const frTranslation = {
     help: 'Aide',
     expand: 'Développer la barre latérale',
     collapse: 'Réduire la barre latérale',
-    updateAvailable: 'Mise à jour disponible',
-    updateReady: '{{version}} est prêt',
-    updateLink: 'Voir la version →',
     downloadingTracks: '{{n}} pistes en cache…',
     offlineLibrary: 'Bibliothèque hors ligne',
     genres: 'Genres',
@@ -328,12 +325,8 @@ export const frTranslation = {
     bulkRemoveFromPlaylist: 'Retirer de la playlist',
     bulkClear: 'Désélectionner',
     updaterAvailable: 'Mise à jour disponible',
-    updaterVersion: 'v{{version}} est prête',
-    updaterInstall: 'Installer & Redémarrer',
-    updaterDownloading: 'Téléchargement…',
-    updaterInstalling: 'Installation…',
-    updaterDownload: 'Télécharger depuis GitHub',
-    updaterExperimentalHint: 'La mise à jour automatique est encore en développement',
+    updaterVersion: 'v{{version}} est disponible',
+    updaterWebsite: 'Site Web',
   },
   settings: {
     title: 'Paramètres',

src/locales/nb.ts

@@ -15,9 +15,6 @@ export const nbTranslation = {
     help: 'Hjelp',
     expand: 'Utvid sidefelt',
     collapse: 'Skjul sidefelt',
-    updateAvailable: 'Ny versjon er tilgjengelig',
-    updateReady: '{{version}} er klar',
-    updateLink: 'Hent nyeste versjon →',
     downloadingTracks: 'Bufre {{n}} spor…',
     offlineLibrary: 'Frakoblet bibliotek',
     genres: 'Sjangere',
@@ -328,12 +325,8 @@ export const nbTranslation = {
     bulkRemoveFromPlaylist: 'Fjern fra spilleliste',
     bulkClear: 'Tøm utvalg',
     updaterAvailable: 'Ny versjon er tilgjengelig',
-    updaterVersion: 'v{{version}} er lansert',
-    updaterInstall: 'Installer og start applikasjonen på nytt',
-    updaterDownloading: 'Laster ned…',
-    updaterInstalling: 'Installerer…',
-    updaterDownload: 'Last ned fra GitHub',
-    updaterExperimentalHint: 'Auto-oppdatering er fortsatt under utvikling',
+    updaterVersion: 'v{{version}} er tilgjengelig',
+    updaterWebsite: 'Nettsted',
   },
   settings: {
     title: 'Innstillinger',

src/locales/nl.ts

@@ -15,9 +15,6 @@ export const nlTranslation = {
     help: 'Help',
     expand: 'Zijbalk uitklappen',
     collapse: 'Zijbalk inklappen',
-    updateAvailable: 'Update beschikbaar',
-    updateReady: '{{version}} is klaar',
-    updateLink: 'Naar release →',
     downloadingTracks: '{{n}} nummers worden gecached…',
     offlineLibrary: 'Offline bibliotheek',
     genres: 'Genres',
@@ -328,12 +325,8 @@ export const nlTranslation = {
     bulkRemoveFromPlaylist: 'Verwijderen uit afspeellijst',
     bulkClear: 'Selectie wissen',
     updaterAvailable: 'Update beschikbaar',
-    updaterVersion: 'v{{version}} is klaar',
-    updaterInstall: 'Installeren & Herstarten',
-    updaterDownloading: 'Downloaden…',
-    updaterInstalling: 'Installeren…',
-    updaterDownload: 'Downloaden van GitHub',
-    updaterExperimentalHint: 'Automatisch bijwerken is nog in ontwikkeling',
+    updaterVersion: 'v{{version}} beschikbaar',
+    updaterWebsite: 'Website',
   },
   settings: {
     title: 'Instellingen',

src/locales/ru.ts

@@ -16,9 +16,6 @@ export const ruTranslation = {
     help: 'Справка',
     expand: 'Развернуть боковую панель',
     collapse: 'Свернуть боковую панель',
-    updateAvailable: 'Доступно обновление',
-    updateReady: '{{version}} готово',
-    updateLink: 'Перейти к релизу →',
     downloadingTracks: 'Кэширование {{n}} треков…',
     offlineLibrary: 'Офлайн-библиотека',
     genres: 'Жанры',
@@ -342,12 +339,8 @@ export const ruTranslation = {
     bulkRemoveFromPlaylist: 'Убрать из плейлиста',
     bulkClear: 'Снять выделение',
     updaterAvailable: 'Доступно обновление',
-    updaterVersion: 'Версия {{version}} готова',
-    updaterInstall: 'Установить и перезапустить',
-    updaterDownloading: 'Скачивание…',
-    updaterInstalling: 'Установка…',
-    updaterDownload: 'Скачать с GitHub',
-    updaterExperimentalHint: 'Автообновление в разработке',
+    updaterVersion: 'Версия {{version}} доступна',
+    updaterWebsite: 'Сайт',
   },
   settings: {
     title: 'Настройки',

src/locales/zh.ts

@@ -15,9 +15,6 @@ export const zhTranslation = {
     help: '帮助',
     expand: '展开侧边栏',
     collapse: '收起侧边栏',
-    updateAvailable: '有可用更新',
-    updateReady: '{{version}} 已就绪',
-    updateLink: '前往发布页面 →',
     downloadingTracks: '正在缓存 {{n}} 首歌曲…',
     offlineLibrary: '离线音乐库',
     genres: '流派',
@@ -324,12 +321,8 @@ export const zhTranslation = {
     bulkRemoveFromPlaylist: '从播放列表移除',
     bulkClear: '取消选择',
     updaterAvailable: '有可用更新',
-    updaterVersion: 'v{{version}} 已就绪',
-    updaterInstall: '安装并重启',
-    updaterDownloading: '下载中…',
-    updaterInstalling: '安装中…',
-    updaterDownload: '从 GitHub 下载',
-    updaterExperimentalHint: '自动更新功能仍在开发中',
+    updaterVersion: 'v{{version}} 已发布',
+    updaterWebsite: '官网',
   },
   settings: {
     title: '设置',