refactor(i18n): split locale files into per-namespace modules (Phase K) (#688)

Each src/locales/<lang>.ts (~1800 LOC) becomes a folder src/locales/<lang>/
with one module per i18n namespace (44 each) plus an index.ts barrel that
reassembles <lang>Translation in the original key order.

Mechanical, script-driven split with a JSON round-trip check: every
locale object is byte-identical to its pre-split form. i18n.ts is
unchanged — './locales/<lang>' now resolves to the folder index.

The per-namespace settings.ts files land ~440-460 LOC; a single i18n
namespace is the natural, non-arbitrary split unit for a flat string
table, so they are intentionally left whole.

src/locales/de/queue.ts

@@ -0,0 +1,45 @@
+export const queue = {
+  title: 'Warteschlange',
+  savePlaylist: 'Playlist speichern',
+  updatePlaylist: 'Playlist aktualisieren',
+  filterPlaylists: 'Playlists filtern…',
+  playlistName: 'Name der Playlist',
+  cancel: 'Abbrechen',
+  save: 'Speichern',
+  loadPlaylist: 'Playlist laden',
+  loading: 'Lade…',
+  noPlaylists: 'Keine Playlists gefunden.',
+  load: 'Warteschlange ersetzen & abspielen',
+  appendToQueue: 'An Warteschlange anhängen',
+  delete: 'Löschen',
+  deleteConfirm: 'Playlist "{{name}}" löschen?',
+  clear: 'Leeren',
+  shuffle: 'Warteschlange mischen',
+  gapless: 'Nahtlos',
+  crossfade: 'Crossfade',
+  infiniteQueue: 'Endlose Warteschlange',
+  autoAdded: '— Automatisch hinzugefügt —',
+  radioAdded: '— Radio —',
+  hide: 'Verbergen',
+  hideNowPlaying: 'Wiedergabeinformationen ausblenden',
+  showNowPlaying: 'Wiedergabeinformationen anzeigen',
+  close: 'Schließen',
+  nextTracks: 'Nächste Titel',
+  shareQueue: 'Warteschlangen-Link kopieren',
+  shareQueueEmpty: 'Die Warteschlange ist leer — nichts zu teilen.',
+  emptyQueue: 'Die Warteschlange ist leer.',
+  trackSingular: 'Titel',
+  trackPlural: 'Titel',
+  showRemaining: 'Restzeit anzeigen',
+  showTotal: 'Gesamtzeit anzeigen',
+  showEta: 'Endzeit anzeigen',
+  replayGain: 'ReplayGain',
+  rgTrack: 'T {{db}} dB',
+  rgAlbum: 'A {{db}} dB',
+  rgPeak: 'Peak {{pk}}',
+  sourceOffline: 'Wiedergabe aus der Offline-Bibliothek',
+  sourceHot: 'Wiedergabe aus dem Cache',
+  sourceStream: 'Wiedergabe aus dem Netzwerkstream',
+  clearCachedLoudnessWaveform: 'Clear cached loudness and waveform, then re-analyze this track',
+  recalculatingLoudnessWaveform: 'Recalculating loudness and waveform for this track…',
+};