Lyrics and karaoke for the music player

- full-screen lyrics view that follows the song: highlighted current line with a colour sweep (word by word when the source has word timing), tap a line to jump, text size, timing nudge, 'Wrong lyrics?' search
- Karaoke mode: the current line large and centered
- lyrics from Plex first, then the bundled Lyrica service (LRCLIB, Musixmatch via Lrcmux, NetEase, Megalobiz); YouTube captions never used; wrong-length recordings refused; answers kept in /data/lyrics
- lyrica/: Lyrica pinned to one commit, built by the workflow as hub-lyrica; compose service sharing the hub's network
- tools/lyrics-test.js

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

README.md

@@ -46,7 +46,7 @@ e.g. hub.necloud.us. Settings: `SEAFILE_URL`, `ONLYOFFICE_URL` env vars in docke
   for iOS 13+, so for most accounts only NE Hub lists are available.
 - **Settings sync**: your preferences (mail addresses, audiobooks sign-in (encrypted), Plex library, Office save location, calendar/task views, recent files) are saved on the server in `/data/settings.json` and shared by every device. The Seafile sign-in token is saved there too (encrypted), so Settings shows Seafile as signed in on every device. Only the music queue stays in the browser.
 - **Search**: libraries, file names (scans libraries if Seafile has no search index) and Plex artists/albums/tracks.
-- **Music**: Plex player. Sign in goes through plex.tv (no password handled), the server proxies your Plex server and adds the token itself, and a mini player keeps playing as you move between tabs; the current and next two tracks are downloaded in full so changing songs is instant and a slow or lost connection does not stop playback; the Music tab shows a Now Playing card with the controls above the albums, artists and playlists; the queue (play next / add to queue) and position are remembered.
+- **Music**: Plex player. Sign in goes through plex.tv (no password handled), the server proxies your Plex server and adds the token itself, and a mini player keeps playing as you move between tabs; the current and next two tracks are downloaded in full so changing songs is instant and a slow or lost connection does not stop playback; the Music tab shows a Now Playing card with the controls above the albums, artists and playlists; the queue (play next / add to queue) and position are remembered. **Lyrics and karaoke**: the Lyrics button (on the Now Playing card, in the full player, and in the wide mini player) opens a full-screen lyrics view that follows the song, tap a line to jump to it, A−/A+ change the size, and **Karaoke** shows just the current line big with the colour sweeping across it as it is sung (word by word when the source has word timing, otherwise across the line). Lyrics come from Plex first if the song has them (embedded, a `.lrc` file next to it, or Plex Pass), otherwise from the bundled **Lyrica** service (`lyrica` container; sources LRCLIB, Musixmatch via Lrcmux, NetEase, Megalobiz; YouTube auto-captions are never used, and an answer for a recording of a very different length is refused). Lookups send the artist and title to those public sources and are kept in `/data/lyrics` so a song is looked up once. If the timing is off, the − / + buttons shift it half a second at a time (remembered per song); "Wrong lyrics?" lets you search with a corrected artist or title. Remove the `lyrica` service and the hub's `LYRICS_API_URL` line to skip the online lookup (Plex lyrics still work). No vocal removal.
 - **Audiobooks**: embeds audiobooks.necloud.us in a frame that keeps playing while you use other tabs, with reload, full screen and open-in-new-tab buttons.
   Back-door sign-in: set `AUDIOBOOKS_LOGIN_LINK` to the site's secret link (the key is part of it). The frame loads `/api/audiobooks/enter`, which checks
   the person may use the Audiobooks tab and redirects to that link, so the key stays in the server's environment and never appears in the app's page,