feat(android): importer 30s preview + partial-album detection

- Importer: each resolved track gets a play/stop button that plays its
  Deezer/Spotify preview via the app-level preview bar (pauses library
  playback, highlights the row). Parity with the web importer.
- Artist "Unvollständig" now works: Deezer's /artist/{id}/albums omits
  nb_tracks, so owned albums never registered as partial. The artist VM
  now resolves the real total for matched albums via a per-album lookup
  (like web), so the partial section + downloaded/missing split populate.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CHANGELOG.md

@@ -73,6 +73,9 @@ like Android), concert events become **reliable across web/Android**, and severa
 - **Unified Global Search field (Web)** — the separate Song-Importer page/sidebar entry is gone. The
   one search field now auto-detects: a **link** (Spotify/SoundCloud/YouTube) opens the importer
   preview, plain **text** runs a Deezer search. Cleaner left nav, same behaviour as Android.
+- **30s preview in the importer (Android)** — each resolved track now has a ▶/⏹ button that plays its
+  Deezer/Spotify preview clip through the same app-level preview bar as Explore (library playback
+  pauses; the row highlights while playing). Parity with the web importer.
 
 ### Fixed
 - **Concert events reliability (Web + Android)** — Ticketmaster's free `keyword` search intermittently
@@ -94,6 +97,12 @@ like Android), concert events become **reliable across web/Android**, and severa
 - **Android artist albums incomplete** — `lookupArtistAlbums` filtered to `record_type == "album"`,
   dropping EPs and singles that Deezer (and the web app) show. Now returns all, sorted album → EP →
   single.
+- **Android "Unvollständig" (partial albums) never showed** — Deezer's `/artist/{id}/albums` omits
+  `nb_tracks`, so an owned album's real total was unknown (0) and it never got flagged incomplete;
+  every partly-downloaded album looked complete. The artist VM now resolves the real track count for
+  **matched (owned)** albums via a per-album lookup (like web), so the "Unvollständig" section — with
+  the downloaded/total badge and the downloaded-vs-missing split screen — populates correctly on both
+  the library and Deezer artist pages.
 - **"Falscher Künstler?" pin button minimised (Web + Android)** — reduced to a small ⚙ icon-only pill
   in the artist hero's corner instead of a full-width labelled button.