Kata phase 3: d3 move-tree in KATA drawer (built from manifest continues_from + localStorage kata-roots); client-side stitch_path; play path/view-move in viewer with playhead sync
Actions library: port the kata web .action-card UI verbatim (scoped); source = signed-in users clips (anon: browser-tracked); del-x deletes (ownership-checked); live play-row transport via iframe<->parent messaging