feat(zones): profile-scoped groups, zone modes, sequence brightness

- Optional profile_id on groups; UI and API for shared vs profile-only groups\n- Zone content_kind (presets vs sequences); edit modal shows matching sections; devices via groups only\n- Server sequence playback folds zone brightness into preset wire b (per MAC where needed)\n- Related preset/sequence/audio/beat-route and client updates

Co-authored-by: Cursor <cursoragent@cursor.com>

src/static/style.css

@@ -1620,6 +1620,14 @@ body.preset-ui-run .edit-mode-only {
     }
 }
 
+.sequence-step-drag-handle:active {
+    cursor: grabbing;
+}
+
+.sequence-step-row.dragging {
+    opacity: 0.65;
+}
+
 /* Settings modal */
 #settings-modal .modal-content {
     max-width: 900px;