feat(cast): music on the TV, the music bar as its remote

A cast button in Music's toolbar and in the music bar. With a television
chosen, each decrypted track goes to the relay with its cover — found as the
album card finds it — and plays there as music with its title, artist and
album; the bar's play, pause, seek, previous and next drive the receiver, its
clock is the receiver's, and the end of a track there moves the queue on.
A film or a photo taking the television pauses the bar; stopping the cast
carries the track on locally.

Photos and tracks now share one path: a whole file sent to the relay in
pieces (binary frames on Android, written to disk there), served at /file
with byte ranges and its cover at /cover, and loaded as what the relay says
it is. cast:image is gone; cast:chromecast:seek is new.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/music-app.js b/packages/meshbay-hub/src/meshbay_hub/static/music-app.js
index 67be344..f2c4374 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/music-app.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/music-app.js
@@ -10,6 +10,7 @@ import { usePager, Pager, pageSizeFrom } from './pager.js';
 import { Menu, MenuDots, useMenu } from './menu.js';
 import { PlaylistMenuButton, NameModal, usePlaylists } from './playlist-menu.js';
 import * as P from './playlists.js';
+import { CastButton } from './cast-session.js';
 
 // -- Music --------------------------------------------------------------------
 //
@@ -747,6 +748,8 @@ function MusicApp({
           lists=${playlists} reload=${reloadPlaylists}
           onPlayQueue=${onPlayQueue} onSync=${syncNow} />`}
         <${Pager} pager=${pager} />
+        ${/* The television the music bar plays to (cast-session.js). */''}
+        <${CastButton} />
         ${!hideFilter && html`<div class="tb-search">
           <${Icon} name="search" />
           <input type="text" placeholder="${t('group.filter')}"