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/index.ts

@@ -0,0 +1,91 @@
+import { sidebar } from './sidebar';
+import { home } from './home';
+import { hero } from './hero';
+import { search } from './search';
+import { nowPlaying } from './nowPlaying';
+import { contextMenu } from './contextMenu';
+import { sharePaste } from './sharePaste';
+import { albumDetail } from './albumDetail';
+import { entityRating } from './entityRating';
+import { artistDetail } from './artistDetail';
+import { favorites } from './favorites';
+import { randomLanding } from './randomLanding';
+import { randomAlbums } from './randomAlbums';
+import { genres } from './genres';
+import { randomMix } from './randomMix';
+import { luckyMix } from './luckyMix';
+import { albums } from './albums';
+import { tracks } from './tracks';
+import { artists } from './artists';
+import { composers } from './composers';
+import { composerDetail } from './composerDetail';
+import { login } from './login';
+import { connection } from './connection';
+import { common } from './common';
+import { settings } from './settings';
+import { changelog } from './changelog';
+import { whatsNew } from './whatsNew';
+import { help } from './help';
+import { queue } from './queue';
+import { miniPlayer } from './miniPlayer';
+import { statistics } from './statistics';
+import { player } from './player';
+import { nowPlayingInfo } from './nowPlayingInfo';
+import { songInfo } from './songInfo';
+import { playlists } from './playlists';
+import { smartPlaylists } from './smartPlaylists';
+import { mostPlayed } from './mostPlayed';
+import { losslessAlbums } from './losslessAlbums';
+import { radio } from './radio';
+import { folderBrowser } from './folderBrowser';
+import { deviceSync } from './deviceSync';
+import { orbit } from './orbit';
+import { tray } from './tray';
+import { licenses } from './licenses';
+
+export const deTranslation = {
+  sidebar,
+  home,
+  hero,
+  search,
+  nowPlaying,
+  contextMenu,
+  sharePaste,
+  albumDetail,
+  entityRating,
+  artistDetail,
+  favorites,
+  randomLanding,
+  randomAlbums,
+  genres,
+  randomMix,
+  luckyMix,
+  albums,
+  tracks,
+  artists,
+  composers,
+  composerDetail,
+  login,
+  connection,
+  common,
+  settings,
+  changelog,
+  whatsNew,
+  help,
+  queue,
+  miniPlayer,
+  statistics,
+  player,
+  nowPlayingInfo,
+  songInfo,
+  playlists,
+  smartPlaylists,
+  mostPlayed,
+  losslessAlbums,
+  radio,
+  folderBrowser,
+  deviceSync,
+  orbit,
+  tray,
+  licenses,
+};