LeoVasanko
3dc438f8df
Rework the site structure tree's drag-and-drop to match Sortable's native
model instead of mid-drag drop zones:
- Drop the dashed empty-list drop zones that appeared on drag start
(flicker, space reservation, and mis-targeted drops: the last item's
child zone sat exactly where 'end of parent list' was).
- Every non-empty list (and the root) ends with a non-draggable ➕ footer
row (vuedraggable #footer slot): click to start a new page at that
level, and while dragging it is the 'end of this list' drop target.
It renders last even mid-drag via flex order, since Sortable appends
end-of-list previews after it in the DOM.
- Dropping ON the lower part of a row makes the page that row's first
child: the child list's container invisibly overlaps its own row's
bottom (negative margin + equal padding, no layout effect) and becomes
hit-testable only while dragging. A row's exposed top strip remains
the 'sibling before' target. Leaf rows work too, creating a sublist.
- Indentation is structural (each nested list margin-indents itself), so
a dragged row previews its whole subtree at the target list's depth.
Rows get a little vertical padding to widen the drop zones.