feat(scrobble): web statistics view (Phase 3 UI)

Opens from Settings ("Meine Statistiken") as a self-contained modal overlay
(no router changes). Fetches GET /scrobble/stats and renders: totals tiles
(plays + listening time), a per-bucket play series, top artists/tracks/albums
with mini bars, and a 24h listening clock. Period tabs (all / this year /
last 30 days) switch from/to + bucket. Vanilla inline SVG-free bars, no chart
lib. Reuses .modal-overlay.open + design tokens; sends local tz offset for
day bucketing. Graceful empty/error/unconfigured states. SW cache -> ns-v65.

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

docs/scrobble-plan.md

@@ -209,9 +209,11 @@ volumes:
    Offline-Queue (Web: localStorage `ns_play_queue`; Android: `filesDir/play-queue.json`),
    idempotenter Batch-Flush bei Start + `online`-Event. `SCROBBLE_URL`/`scrobbleUrl` in beiden
    Settings. Web-Build + Android-`compileDebugKotlin` grün. *Ab jetzt wird real erfasst.*
-3. 🔨 **In Arbeit**: `/scrobble/stats` ✅ (Endpoint: totals, Top-Listen, day/month/year-Serie,
-   Hör-Uhr; on-the-fly `GROUP BY strftime`, tz-Offset, unit-getestet) — **noch offen: Web-Statistik-View**
-   (Kalender-Heatmap, Monats-Balken, Top-Listen).
+3. ✅ **Erledigt**: `/scrobble/stats` (Endpoint: totals, Top-Listen, day/month/year-Serie, Hör-Uhr;
+   on-the-fly `GROUP BY strftime`, tz-Offset, unit-getestet) **+ Web-Statistik-View**
+   ([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.
 5. *(optional)* ListenBrainz-Relay.