The Objects panel shows the object graph with type icons and a
right-click menu (open, create, paste, copy link, rename, remove).
Selecting an object shows its editor in the center. The preview panel
and the list/tree tabs are gone.
Debugging adds Bytecode and Runtime panels to the main dock once and
only refreshes their content on each step, keeping the selected
runtime tab. The panels are removed when execution ends.
ListObject::delNode now unlinks the node before freeing it.
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