feat: partial album split view + artist page full-screen + Bibliothek iTunes integration

- Partial album detail: tapping incomplete albums now shows downloaded songs
  (normal playback) above and missing iTunes tracks (30s preview + download)
  below — on both Android and web PWA
- Android: ItunesArtistScreen now renders full-screen above the tab/search bar
- Android: ArtistDetailScreen (Bibliothek) now loads iTunes data in parallel —
  adds Weltweit populär section and In Library/Unvollständig/Nicht heruntergeladen
  album sections identical to the Erkunden artist page
- Fix: artist no longer appears in its own Similar Artists row
- Fix: duplicate album entries deduplicated by collectionId in categorizeAlbums

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

src/themes.js

@@ -1,5 +1,5 @@
 const THEME_KEY = 'ns_theme';
-const DEFAULT_ID = 'dark-amber';
+const DEFAULT_ID = 'dark-ocean';
 
 export const THEMES = [
   {

src/views/detail.js

@@ -291,7 +291,7 @@ function _renderArtistAlbums(el, ndAlbums, iAlbums, artist) {
       const art = itunes?.artworkUrl100?.replace('100x100','512x512') || coverUrl(nd.coverArt, 512);
       const c = makeCard(nd.name, `${have} / ${total} Tracks`, art, '💿');
       c.querySelector('.card-art').onclick = (e) => { e.stopPropagation(); quickPlayAlbum(nd); };
-      c.querySelector('.card-info').onclick = () => itunes ? navigate('itunes-album-detail', itunes) : navigate('album-detail', { ...nd, _fromArtist: artist });
+      c.querySelector('.card-info').onclick = () => itunes ? navigate('partial-album-detail', { nd, itunes }) : navigate('album-detail', { ...nd, _fromArtist: artist });
       const artEl = c.querySelector('.card-art');
       const badge = document.createElement('div');
       badge.className = 'album-partial-badge'; badge.textContent = `${have}/${total}`;
@@ -376,6 +376,75 @@ export async function loadItunesAlbumDetail(album) {
   } catch(e) { sl.innerHTML = `<p style="color:var(--danger)">${e.message}</p>`; }
 }
 
+export async function loadPartialAlbumDetail({ nd, itunes }) {
+  document.getElementById('partial-album-back-btn').onclick = () => _navGoBack();
+  document.getElementById('partial-album-detail-name').textContent = nd.name || '—';
+  document.getElementById('partial-album-detail-artist').textContent = nd.artist || itunes?.artistName || '';
+  const art = (itunes?.artworkUrl100 || '').replace('100x100bb','600x600bb').replace('100x100','600x600')
+    || (nd.coverArt ? coverUrl(nd.coverArt, 512) : '');
+  const cw = document.getElementById('partial-album-cover-wrap');
+  cw.innerHTML = art ? `<img src="${art}" onerror="_imgRetry(this,'💿')">` : '<div class="no-art">💿</div>';
+
+  const dlEl    = document.getElementById('partial-album-downloaded');
+  const missEl  = document.getElementById('partial-album-missing');
+  const statsEl = document.getElementById('partial-album-detail-stats');
+  dlEl.innerHTML = missEl.innerHTML = '<div class="spinner"></div>';
+
+  try {
+    const [ndRes, iTracks] = await Promise.all([
+      api('getAlbum', `&id=${nd.id}`),
+      itunes?.collectionId ? itunesLookupAlbum(itunes.collectionId) : Promise.resolve([]),
+    ]);
+    const ndSongs = (ndRes.album?.song || []).sort((a,b) => (a.track||999)-(b.track||999));
+
+    // Cross-reference by normalized track name
+    const norm = s => (s||'').toLowerCase().replace(/[^a-z0-9]/g,'').trim();
+    const ndNames = new Set(ndSongs.map(s => norm(s.title)));
+    const missing = iTracks.filter(t => !ndNames.has(norm(t.trackName))).sort((a,b)=>(a.trackNumber||999)-(b.trackNumber||999));
+
+    statsEl.textContent = `${ndSongs.length} heruntergeladen · ${missing.length} fehlen`;
+
+    // Play button plays downloaded songs
+    document.getElementById('partial-album-play-btn').onclick = () => {
+      if(ndSongs.length) playQueue(ndSongs, 0);
+    };
+
+    // Download button offers missing via iTunes
+    document.getElementById('partial-album-dl-btn').onclick = () => {
+      if(itunes) openDlModal({ artistName: itunes.artistName, trackName: itunes.collectionName, collectionName: itunes.collectionName, artworkUrl100: itunes.artworkUrl100||'', isAlbum: true, itunesData: itunes, collectionId: itunes.collectionId });
+    };
+
+    // Section: downloaded
+    dlEl.innerHTML = '';
+    if(ndSongs.length) {
+      const h = document.createElement('div');
+      h.className = 'section-title';
+      h.style.cssText = 'margin:16px 0 8px';
+      h.innerHTML = `Heruntergeladen <span class="section-count">${ndSongs.length}</span>`;
+      dlEl.appendChild(h);
+      const list = document.createElement('div'); list.className = 'song-list'; dlEl.appendChild(list);
+      ndSongs.forEach((s,i) => list.appendChild(makeSongItem(s, i, ndSongs)));
+    }
+
+    // Section: missing
+    missEl.innerHTML = '';
+    if(missing.length) {
+      const h = document.createElement('div');
+      h.className = 'section-title';
+      h.style.cssText = 'margin:16px 0 8px;opacity:0.7';
+      h.innerHTML = `Nicht heruntergeladen <span class="section-count">${missing.length}</span>`;
+      missEl.appendChild(h);
+      const list = document.createElement('div'); list.className = 'song-list'; missEl.appendChild(list);
+      missing.forEach((t,i) => list.appendChild(makeGlobalTrackItem(t, i, missing)));
+    } else {
+      missEl.innerHTML = '';
+    }
+  } catch(e) {
+    dlEl.innerHTML = `<p style="color:var(--danger)">${e.message}</p>`;
+    missEl.innerHTML = '';
+  }
+}
+
 // ─── ALBUM DETAIL ───
 export async function loadAlbumDetail(album) {
   if (S.cfg.showRomaji) await ensureArtistSortMap().catch(() => {});

src/views/navigation.js

@@ -5,7 +5,7 @@ import { loadSpotifyImporter } from './spotify.js';
 import { loadSoundCloudImporter } from './soundcloud.js';
 // Circular — safe (all calls happen inside function bodies)
 import { loadHomeData, loadAlbumRow, loadArtists, loadAlbums, loadGenreDetail } from './home.js';
-import { loadArtistDetail, loadArtistAllSongs, loadAlbumDetail, loadItunesAlbumDetail } from './detail.js';
+import { loadArtistDetail, loadArtistAllSongs, loadAlbumDetail, loadItunesAlbumDetail, loadPartialAlbumDetail } from './detail.js';
 import { loadPlaylists, loadPlaylistDetail, loadStarred, loadRandom } from './playlists.js';
 import { loadNewReleases, loadRecommendations } from './discover.js';
 
@@ -57,7 +57,8 @@ export function navigate(page, data=null) {
   if(page==='artist-all-songs'   && data) loadArtistAllSongs(data);
   if(page==='album-detail'       && data) loadAlbumDetail(data);
   if(page==='genre-detail'       && data) loadGenreDetail(data);
-  if(page==='itunes-album-detail'&& data) loadItunesAlbumDetail(data);
+  if(page==='itunes-album-detail'  && data) loadItunesAlbumDetail(data);
+  if(page==='partial-album-detail' && data) loadPartialAlbumDetail(data);
   if(page==='new-releases')  loadNewReleases();
   if(page==='playlists')     loadPlaylists();
   if(page==='playlist-detail' && data) loadPlaylistDetail(data);