feat(queue): make queue tracks draggable via dnd-kit

Wire up @dnd-kit sortable context in QueuePanel so tracks can be
reordered by dragging the grip handle, dispatching moveInQueue on drop.

src/styles/shell.css

@@ -668,6 +668,12 @@
   );
   box-shadow: 0 0 0 1px rgba(190, 242, 100, 0.35) inset;
 }
+.qrow.dragging {
+  z-index: 1;
+  cursor: grabbing;
+  background: rgba(255, 255, 255, 0.06);
+  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.4);
+}
 .qrow.current .qt .t {
   color: var(--lime);
   font-weight: 600;