Context menu insertion before floatingPanel shifted its fragment index,
causing React to unmount/recreate the DOM element on DM↔space transitions.
The ResizeObserver was left observing the old detached element, so
paddingBottom never adjusted and channels scrolled behind the panel.
- Reorder fragment children so floatingPanel is at index 1 in both views
- Replace useRef with callback ref so ResizeObserver reattaches on remount
- Add stopPropagation to ContextMenu to prevent sidebar menu conflicts
- Restyle sidebar create channel/category buttons (smaller, separated)