fix(base-ui): keep menu labels inside a Menu.Group

Menu.GroupLabel requires a Menu.Group ancestor, which radix's
DropdownMenu.Label did not. Four labels were orphaned and threw
"MenuGroupContext is missing" as soon as those menus opened.

"Workspaces" moves into the group it labels; the standalone headings
("My account", "lena@foomo.org", "Toggle columns") each get their own
group so the visual order is unchanged.

The first QA pass missed this because it opened only the Notifications
menu, which has no label. Replaced with a sweep over every overlay
trigger in every story and tab panel at two viewports: 203 layers, 0
errors.

src/components/data-table.tsx

@@ -385,7 +385,9 @@ function DataTable<
 								}
 							/>
 							<DropdownMenuContent align="end" className="lib:w-44">
-								<DropdownMenuLabel>Toggle columns</DropdownMenuLabel>
+								<DropdownMenuGroup>
+									<DropdownMenuLabel>Toggle columns</DropdownMenuLabel>
+								</DropdownMenuGroup>
 								<DropdownMenuSeparator />
 								<DropdownMenuGroup>
 									{table

src/stories/Dashboard.stories.tsx

@@ -487,8 +487,8 @@ function AppSidebar() {
 								}
 							/>
 							<DropdownMenuContent align="start" className="lib:w-56">
-								<DropdownMenuLabel>Workspaces</DropdownMenuLabel>
 								<DropdownMenuGroup>
+									<DropdownMenuLabel>Workspaces</DropdownMenuLabel>
 									<DropdownMenuItem>
 										<Building2 />
 										Foomo Inc.
@@ -642,7 +642,9 @@ function AppSidebar() {
 								align="start"
 								className="lib:w-56"
 							>
-								<DropdownMenuLabel>My account</DropdownMenuLabel>
+								<DropdownMenuGroup>
+									<DropdownMenuLabel>My account</DropdownMenuLabel>
+								</DropdownMenuGroup>
 								<DropdownMenuSeparator />
 								<DropdownMenuGroup>
 									<DropdownMenuItem>
@@ -750,7 +752,9 @@ function DashboardHeader({ onOpenCommand }: { onOpenCommand: () => void }) {
 						}
 					/>
 					<DropdownMenuContent align="end" className="lib:w-56">
-						<DropdownMenuLabel>lena@foomo.org</DropdownMenuLabel>
+						<DropdownMenuGroup>
+							<DropdownMenuLabel>lena@foomo.org</DropdownMenuLabel>
+						</DropdownMenuGroup>
 						<DropdownMenuSeparator />
 						<DropdownMenuGroup>
 							<DropdownMenuItem>