feat(hub): big monochrome disc placeholder for covers with no art

Album tiles/detail covers with no embedded art, no sibling image file,
and no MusicBrainz match (or MusicBrainz off) used the same small
music-note icon list rows use elsewhere - fine as a rare fallback, but
most tiles in a real library land here, so it read as broken rather
than as the default look of the grid.

- icon.js: a "disc" icon (two concentric circles, same stroked style
  as the rest of the set) - a plain CD/vinyl glyph.
- music-app.js: AlbumCard and MusicDetailModal's cover now pass
  emptyIcon="disc" instead of "music".
- style.css: sized at 55% of the tile via CSS rather than a fixed px
  value, so it scales with .music-grid's auto-fill columns; color
  stays var(--text-dim), the same neutral tone every other empty state
  already uses - monochrome, not a new accent.

Client-side only. npm run sync-ui re-run. Full suite: 1129 passed, no
regressions.

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

3 files changed, 19 insertions, 2 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/icon.js b/packages/meshbay-hub/src/meshbay_hub/static/icon.js
index 0ecbd70..87b56ee 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/icon.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/icon.js
@@ -74,6 +74,8 @@ const ICON_PATHS = {
   music:    ['M9 18V5l12-2v13',
              'M4 18a2 2 0 1 0 4 0 2 2 0 1 0 -4 0',
              'M16 16a2 2 0 1 0 4 0 2 2 0 1 0 -4 0'],
+  disc:     ['M3 12a9 9 0 1 0 18 0 9 9 0 1 0 -18 0',
+             'M9 12a3 3 0 1 0 6 0 3 3 0 1 0 -6 0'],
   pause:    ['M7 5.5v13', 'M17 5.5v13'],
   'skip-next': ['M5 4l10 8-10 8z', 'M19 5v14'],
   'skip-prev': ['M19 4L9 12l10 8z', 'M5 5v14'],
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 77023b3..b8ee657 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/music-app.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/music-app.js
@@ -123,7 +123,7 @@ function AlbumCard({ album, transportRef, gekRef, musicbrainzEnabled, onOpen })
   return html`
     <div class="music-card" onClick=${onOpen}>
       <${MediaThumb} thumbHash=${coverHash} alt=${album.album}
-        cls="music-cover" emptyIcon="music"
+        cls="music-cover" emptyIcon="disc"
         transportRef=${transportRef} gekRef=${gekRef} />
       <div class="music-card-info">
         <div class="music-card-title">${album.album}</div>
@@ -154,7 +154,7 @@ function MusicDetailModal({ album, transportRef, gekRef, musicbrainzEnabled, onC
         <div class="music-detail-body">
           <div class="music-detail-header">
             <${MediaThumb} thumbHash=${coverHash} alt=${album.album}
-              cls="music-detail-cover" emptyIcon="music"
+              cls="music-detail-cover" emptyIcon="disc"
               transportRef=${transportRef} gekRef=${gekRef} />
             <div class="music-detail-meta">
               <div class="music-detail-artist">${album.artist}</div>
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/style.css b/packages/meshbay-hub/src/meshbay_hub/static/style.css
index b4e4089..6c3c0f6 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/style.css
+++ b/packages/meshbay-hub/src/meshbay_hub/static/style.css
@@ -2727,6 +2727,16 @@ a.transfer-name {
   background: var(--bg-surface);
 }
 .music-cover.video-thumb-empty { aspect-ratio: 1 / 1; }
+/* A big, plain disc rather than the small note icon shared with list rows —
+   most tiles land here (few files carry embedded/sibling art), so this is
+   the default look of the grid, not a rare fallback; it needs to read as
+   deliberate, not broken. Sized relative to the tile so it scales with
+   .music-grid's auto-fill columns instead of one fixed px value. */
+.music-cover.video-thumb-empty .icon {
+  width: 55%;
+  height: 55%;
+  color: var(--text-dim);
+}
 
 .music-card-info { padding: 8px 10px; }
 .music-card-title {
@@ -2782,6 +2792,11 @@ a.transfer-name {
   flex-shrink: 0;
   background: var(--bg-raised);
 }
+.music-detail-cover.video-thumb-empty .icon {
+  width: 55%;
+  height: 55%;
+  color: var(--text-dim);
+}
 .music-detail-meta { min-width: 0; }
 .music-detail-artist { font-weight: 600; font-size: 0.95em; }
 .music-detail-date { font-size: 0.8em; color: var(--text-dim); margin: 2px 0 8px; }