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/nl/nowPlaying.ts

@@ -0,0 +1,47 @@
+export const nowPlaying = {
+  tooltip: 'Wie luistert er?',
+  title: 'Wie luistert er?',
+  loading: 'Laden…',
+  nobody: 'Er luistert momenteel niemand.',
+  minutesAgo: '{{n}} min geleden',
+  nothingPlaying: 'Nog niets bezig. Start een nummer!',
+  aboutArtist: 'Over de artiest',
+  fromAlbum: 'Van dit album',
+  viewAlbum: 'Album openen',
+  goToArtist: 'Naar artiest',
+  readMore: 'Meer lezen',
+  showLess: 'Minder tonen',
+  genreInfo: 'Genre',
+  trackInfo: 'Trackinfo',
+  topSongs: 'Meest afgespeeld van deze artiest',
+  topSongsCredit: 'Topnummers van {{name}}',
+  trackPosition: 'Track {{pos}}',
+  playsCount_one: '{{count}} keer afgespeeld',
+  playsCount_other: '{{count}} keer afgespeeld',
+  releasedYearsAgo_one: '{{count}} jaar geleden',
+  releasedYearsAgo_other: '{{count}} jaar geleden',
+  discography: 'Discografie',
+  lastfmStats: 'Last.fm-statistieken',
+  thisTrack: 'Dit nummer',
+  thisArtist: 'Deze artiest',
+  listeners: 'luisteraars',
+  scrobbles: 'scrobbles',
+  yourScrobbles: 'door jou',
+  listenersN: '{{n}} luisteraars',
+  scrobblesN: '{{n}} scrobbles',
+  playsByYouN: '{{n}}× door jou afgespeeld',
+  openTrackOnLastfm: 'Nummer op Last.fm',
+  openArtistOnLastfm: 'Artiest op Last.fm',
+  rgTrackTooltip: 'ReplayGain (track)',
+  rgAlbumTooltip: 'ReplayGain (album)',
+  rgAutoTooltip: 'ReplayGain (auto)',
+  showMoreTracks: '{{count}} meer tonen',
+  showLessTracks: 'Minder tonen',
+  hideCard: 'Kaart verbergen',
+  layoutMenu: 'Lay-out',
+  visibleCards: 'Zichtbare kaarten',
+  hiddenCards: 'Verborgen kaarten',
+  noHiddenCards: 'Geen verborgen kaarten',
+  resetLayout: 'Lay-out resetten',
+  emptyColumn: 'Sleep kaarten hier',
+};