music: play, play next, add to queue

The player's queue could only be replaced: every onPlayQueue reset
tracks/order/pos together. It becomes one reducer (queue-ops.js) with
an `op`, because two appends batched into one tick cannot both read the
track count out of separate useStates.

A shared pop-up menu (menu.js) carries the three verbs, on right-click
and on a dots button. A track row is now a div holding two buttons: a
button cannot contain a button.

Found by the browser probe: both music wrappers took two arguments and
forwarded two, so every "add to queue" arrived as a plain play.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/icon.js b/packages/meshbay-hub/src/meshbay_hub/static/icon.js
index f45d339..ad9fb82 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/icon.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/icon.js
@@ -100,6 +100,12 @@ const ICON_PATHS = {
                'M8 11h6'],
   frame: ['M4 9V5a1 1 0 0 1 1-1h4', 'M15 4h4a1 1 0 0 1 1 1v4',
           'M20 15v4a1 1 0 0 1-1 1h-4', 'M9 20H5a1 1 0 0 1-1-1v-4'],
+  // A list with a plus: the playlist verbs, and the one button Music's
+  // toolbar can spare for them (docs/playlists.md §10.3).
+  playlist: ['M4 7h12', 'M4 12h12', 'M4 17h7', 'M17.5 14.5v6', 'M14.5 17.5h6'],
+  // A list with a play head at its foot — "after this one", as distinct from
+  // `play` (start now) and `plus` (at the end).
+  playnext: ['M4 7h10', 'M4 12h10', 'M4 17h6', 'M15.5 13.5v7l5.5-3.5z'],
 };
 
 // The M of the wordmark is a picture; the rest is text. Resolved from this