docs: v2.0 — document the scrobble / listening-stats system

- CHANGELOG: new [2.0] entry (own timestamped play-log service, stats view on
  web + android with cover art, remix-dedup fix, user-select UI fix, node 20->22);
  Platform Parity Matrix gains play-log / stats / stats-cover rows (+ Wrapped 🔜).
- README: Listening stats feature, scrobble/ in the project tree, SCROBBLE_URL
  env + scrobble container table, port 3710 + SSO-exclusion note in setup.
- CLAUDE.md: new 'Listening stats / scrobble system' section (isolation rationale,
  node:sqlite gotchas, ping.view multi-user auth, capture point, cover resolution,
  SSO deploy gotcha).

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

README.md

@@ -15,6 +15,7 @@ Built with Vite + vanilla ES modules (web) and Jetpack Compose + Media3/ExoPlaye
 - **Importer & downloads** — Paste a Spotify / YouTube / YouTube Music / SoundCloud link to download via yt-dlp, with Deezer metadata enrichment and duplicate detection.
 - **Metadata editor** (web) — Edit tags + cover art; files are renamed/moved and Navidrome is rescanned on save.
 - **Offline** (Android) — Download albums, playlists, or single songs to private storage; an Offline tab to play and manage them (works without a server connection); downloaded tracks play from disk on every screen.
+- **Listening stats** — A separate, self-hosted scrobble service records **timestamped plays** (multi-user; Navidrome only keeps a play *count*). A statistics view (Web + Android, from Settings) shows totals, top artists/tracks/albums with cover art, a day/month/year play series, and a 24h listening clock. Runs *in addition to* Navidrome/Last.fm scrobbling.
 - **Audiobookshelf** — Browse and stream audiobooks with chapter navigation, speed control, sleep timer, and progress sync.
 
 Web is an installable PWA (themes, German UI); Android is native Jetpack Compose + Media3/ExoPlayer with a mini player, media/ABS notifications, and Android Auto. See [CHANGELOG.md](CHANGELOG.md) for the full web/Android parity matrix.
@@ -28,7 +29,8 @@ NovaSonic/
 ├── src/
 │   ├── player/
 │   │   ├── player.js          # Playback, queue, transport, media session, preload
-│   │   └── nowplaying.js      # Now Playing overlay + synced lyrics
+│   │   ├── nowplaying.js      # Now Playing overlay + synced lyrics
+│   │   └── scrobbleLog.js     # Play-log capture + offline queue → scrobble service
 │   ├── views/
 │   │   ├── detail.js          # Artist / album detail pages
 │   │   ├── views.js           # Navigation, page loaders, search
@@ -48,6 +50,7 @@ NovaSonic/
 │   │   ├── metadata.js        # Metadata editor
 │   │   ├── modals.js          # Song info, events modals
 │   │   ├── notify.js          # Toast notifications
+│   │   ├── stats.js           # Listening statistics view (overlay)
 │   │   └── settings.js        # Settings page
 │   ├── state.js               # Shared mutable state (S object)
 │   ├── utils.js               # Helpers (md5, esc, formatDur, toast)
@@ -63,6 +66,8 @@ NovaSonic/
 │       ├── ytdlp.js           # yt-dlp download + ffmpeg metadata embedding
 │       ├── downloader.js      # Unified downloadTrack / downloadAlbumTracks
 │       └── romaji.js          # Japanese → romaji search index
+├── scrobble/                  # Isolated listening-stats service (own container + DB)
+│   └── scrobble-server.js     # node:sqlite play-log: ingest / history / stats / health
 ├── android/                   # Native Android app (Jetpack Compose + Media3)
 │   └── app/src/main/kotlin/com/novasonic/app/
 │       ├── api/               # SubsonicClient, AbsClient, LrcLibClient, ItunesClient (Deezer-backed)
@@ -84,7 +89,7 @@ NovaSonic/
 ├── Dockerfile
 ├── docker-compose.yml
 ├── nginx.conf
-└── docker-entrypoint.sh       # Injects NAVIDROME_URL / BACKEND_URL at runtime
+└── docker-entrypoint.sh       # Injects NAVIDROME_URL / BACKEND_URL / SCROBBLE_URL at runtime
 ```
 
 ---
@@ -104,6 +109,7 @@ Edit `.env`:
 ```env
 NAVIDROME_URL=https://music.yourdomain.com
 BACKEND_URL=https://novasonic-api.yourdomain.com
+SCROBBLE_URL=https://novasonic-scrobble.yourdomain.com   # listening-stats service
 
 MUSIC_PATH=/srv/navidrome/music
 
@@ -120,7 +126,7 @@ TICKETMASTER_API_KEY=  # optional — free key from developer.ticketmaster.com
 docker compose up -d
 ```
 
-Frontend on port 8080, backend on port 3700. Route both through your reverse proxy.
+Frontend on port 8080, backend on port 3700, scrobble service on port 3710. Route each through your reverse proxy. **Important:** the scrobble subdomain must *not* sit behind an SSO / forward-auth gateway — it authenticates itself via Navidrome (`ping.view`), and a gateway in front redirects the app's API calls to a login page.
 
 ### 3. First launch
 
@@ -128,6 +134,7 @@ Frontend on port 8080, backend on port 3700. Route both through your reverse pro
 2. Optionally add a Last.fm API key in Settings for bios and recommendations
 3. Optionally connect Audiobookshelf in Settings
 4. Optionally add the NovaSonic backend URL in Settings to enable downloads
+5. Optionally add the NovaSonic scrobble URL in Settings to record listening stats
 
 ---
 
@@ -139,6 +146,7 @@ Frontend on port 8080, backend on port 3700. Route both through your reverse pro
 |---|---|
 | `NAVIDROME_URL` | Pre-fills the Navidrome server URL on the login screen |
 | `BACKEND_URL` | Pre-fills the download backend URL on the login screen |
+| `SCROBBLE_URL` | Pre-fills the listening-stats (scrobble) service URL on the login screen |
 
 ### Backend container
 
@@ -151,6 +159,14 @@ Frontend on port 8080, backend on port 3700. Route both through your reverse pro
 | `MAX_PARALLEL` | `2` | Max concurrent download jobs |
 | `TICKETMASTER_API_KEY` | — | Free key from [developer.ticketmaster.com](https://developer.ticketmaster.com) |
 
+### Scrobble container
+
+| Variable | Default | Description |
+|---|---|---|
+| `PORT` | `3710` | Port the scrobble service listens on |
+| `DATA_PATH` | `/data` | Where the play-log SQLite DB is stored (own volume) |
+| `NAVIDROME_URL` | — | Used to verify user credentials via `ping.view` (multi-user auth) |
+
 ---
 
 ## Development