feat(hub): Music app client — album grid, flat list, persistent player

Implements the client half of docs/musicbay.md against MNP 0.8:

- music-app.js: album grid (grouped by artist -> album, from index-time
  artist/album fields) or flat folder view, per-group localStorage
  toggle like Videos. MusicBrainz (music_meta_req) is only looked up
  when a track has no embedded cover at all — well-tagged files never
  trigger a network call, unlike Videos where TMDB is unconditional.
  Reuses video-app.js's MediaThumb/LazyTile (now exported) rather than
  duplicating the chunk-path thumbnail decode + virtualization.
- music-player.js: the persistent player bar — queue, shuffle (Fisher-
  Yates, keeps the current track in place when toggled), repeat (off/
  all/one), volume (localStorage), prev/next, a one-track prefetch
  cache. No MSE, no node-side streaming: a track is downloaded and
  decrypted once via file-utils.js's pipelinedDownload, same chunk
  pipeline Files already uses, then played from a blob URL.
- group-page.js: owns musicQueue/musicbrainzConfig state and renders
  MusicPlayerBar outside the tab-switched area — deliberately, so
  playback survives navigating to Chat/Files, the same reasoning the
  video/preview modals are shell-owned rather than app-owned.
- apps.js: registers "music". transport.js: fetchMusicMeta (keyed by
  path, same reordering-hazard fix as fetchMediaMeta),
  setMusicbrainzConfig/setMusicbrainzEnabled (signed ops, mirroring
  TMDB's), and the three new ack handlers. group-settings.js: a
  MusicBrainz settings section (contact string, per-group toggle) —
  the existing Applications checklist already picks up "music" for
  free, per apps.md's own claim.
- icon.js: music/pause/skip-next/skip-prev/shuffle/repeat/volume,
  drawn in the same stroked style as the existing set.
- i18n: group.tab_music, the music.* and settings_node.musicbrainz_*
  keys, translated (not just copied) across all ten locales, Polish
  carrying full one/few/many/other plural forms for music.n_tracks.
- webapp.py's _ASSETS, test_hook_ordering.py's STATIC_FILES and
  test_transport_contracts.py's SPLIT_FILES gain the two new files.

Full suite (common + hub + node): 1116 passed, no regressions.
`npm run sync-ui` in meshbay-client confirmed both files copied.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KBi7ALLGfwcjBXt57yNMcy

1 files changed, 31 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
index bdfda75..257318a 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
@@ -76,6 +76,7 @@ export default {
   'group.tab_files': 'File',
   'group.tab_chat': 'Chat',
   'group.tab_video': 'Video',
+  'group.tab_music': 'Musica',
   'group.tab_members': 'Membri',
   'group.tab_settings': "Impostazioni",
   'members.danger_leave_hint': "Perderai l’accesso ai file e alla chat di questo gruppo.",
@@ -175,6 +176,27 @@ export default {
   'video.search_no_results': 'Nessuna corrispondenza trovata.',
   'video.search_apply_hint': 'Si applica a tutti i file attualmente raggruppati sotto questo titolo.',
 
+  // Musica
+  'music.mode_grid': 'Album',
+  'music.mode_flat': 'Elenco semplice',
+  'music.empty': 'Nessuna musica trovata.',
+  'music.unknown_album': 'Album sconosciuto',
+  'music.play_all': 'Riproduci tutto',
+  'music.n_tracks': {
+    one: '{n} traccia',
+    other: '{n} tracce',
+  },
+  'music.err_transport': 'Trasporto non connesso',
+  'music.player_play': 'Riproduci',
+  'music.player_pause': 'Pausa',
+  'music.player_prev': 'Precedente',
+  'music.player_next': 'Successivo',
+  'music.player_shuffle': 'Riproduzione casuale',
+  'music.player_repeat_off': 'Ripetizione disattivata',
+  'music.player_repeat_all': 'Ripeti tutto',
+  'music.player_repeat_one': 'Ripeti brano',
+  'music.player_volume': 'Volume',
+
   // LAN cast
   'cast.start': 'Trasmetti al dispositivo',
   'cast.stop': 'Interrompi trasmissione',
@@ -614,6 +636,15 @@ export default {
   'settings_node.video_root_title': 'Cartella radice di Video',
   'settings_node.video_root_hint': "Quale cartella (o sottocartella) l'app Video considera come punto di ingresso per questo gruppo. In Video non viene mostrato nulla, e non viene eseguita alcuna ricerca TMDB, finché non ne viene scelta una.",
   'settings_node.video_root_none': '— nessuna scelta —',
+  'settings_node.musicbrainz_title': 'Metadati MusicBrainz',
+  'settings_node.musicbrainz_hint': "Permette all'app Musica di mostrare copertine e nomi canonici da MusicBrainz quando una traccia non ha una copertina incorporata utilizzabile. Disattivato significa navigazione basata solo su tag/nome file, senza richieste a terzi.",
+  'settings_node.musicbrainz_enabled': 'Attivato',
+  'settings_node.musicbrainz_disabled': 'Disattivato',
+  'settings_node.musicbrainz_contact_label': 'Contatto (necessario perché MusicBrainz risponda)',
+  'settings_node.musicbrainz_contact_placeholder': 'tu@esempio.com o un URL di progetto',
+  'settings_node.musicbrainz_contact_set': 'È configurato un contatto.',
+  'settings_node.musicbrainz_contact_unset': 'Nessun contatto configurato — le ricerche MusicBrainz restano disattivate finché non ne viene impostato uno.',
+  'settings_node.musicbrainz_save': 'Salva',
   'settings_node.video_root_save': 'Salva',
   'settings_node.video_root_change_confirm': 'Cambiare la radice di Video sostituisce ciò che ogni membro vede nella scheda Video. Continuare?',