* Studio: fix nested dropdown submenus clipped by the menu alignment nudge
The 3px alignment nudge on DropdownMenuContent used translate, which
makes the scroll container the containing block for nested
position:fixed submenu wrappers, so overflow clipped every submenu
(plus menu More and Projects, sidebar chat menus, Recents export).
Use margin for the same visual shift without a containing block.
* Portal dropdown submenus so ancestor styling can never clip them
Rendered inline, the fixed submenu wrapper lives inside the parent
menu's scroll container, so any transform there (like the 3px nudge)
re-enables overflow clipping. Portaling to body removes the submenu
from that subtree entirely, same as DropdownMenuContent.
3cd0b9b18e