feat(scrobble): Android stats screen + cover art in stats (web + android)

Phase 4 (part B): Android statistics screen consuming GET /scrobble/stats —
tiles (plays + listening time), day/month/year play series, top artists/tracks/
albums, 24h listening clock, period tabs; opened from a Settings button
("Meine Statistiken"). New StatsViewModel + StatsScreen + ScrobbleModels;
PlayLogClient.fetchStats() (tolerant JSON decode, null on any failure);
repo.fetchScrobbleStats(); nav route + SettingsScreen(onOpenStats).

Cover art everywhere: top artists show a circular artist image, tracks/albums
a square cover — resolved client-side from Navidrome via artistId/albumId/songId
(no coverArt knowledge in the scrobble service). Endpoint now also returns
albumId for top tracks so track covers resolve reliably. Web stats list gets the
same thumbnails. SW cache -> ns-v67.

Android compileDebugKotlin + web build green. Needs on-device runtime test.

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

docs/scrobble-plan.md

@@ -214,7 +214,12 @@ volumes:
    ([src/ui/stats.js](../src/ui/stats.js)) — Overlay aus den Einstellungen („📊 Meine Statistiken"),
    Zeitraum-Tabs (Alles / Dieses Jahr / Letzte 30 Tage), Kacheln, Verlaufs-Balken, Top-Listen,
    Hör-Uhr. Vanilla/inline, keine Chart-Lib. **Braucht Runtime-Test am Gerät.**
-4. **`/scrobble/wrapped`** + Story-Seite; Android-Stats-Screen.
+4. 🔨 **In Arbeit**: **Android-Stats-Screen** ✅ (konsumiert `/scrobble/stats`; Kacheln, Verlaufs-
+   Balken, Top-Listen, Hör-Uhr; Zeitraum-Tabs; aus den Android-Einstellungen). **Cover + Artist-
+   Bilder** ✅ in Web **und** Android (client-seitig aus Navidrome via `coverUrl`/`coverArtUrl` über
+   `artistId`/`albumId`/`songId`; Endpoint liefert jetzt auch `albumId` bei Top-Tracks).
+   **Noch offen: Wrapped** (`/scrobble/wrapped` + Web-Story-Seite). Android + Web build grün;
+   **braucht Runtime-Test am Gerät.**
 5. *(optional)* ListenBrainz-Relay.
 
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