fix(ui): drop the focus ring on tab panels

Radix gives the content element focus when a tab is selected, so the
focus-visible ring fired on an ordinary click and outlined the whole
lower pane — visible as an orange rule under the tab strip. A tab panel
is a container; the controls inside it carry their own focus styling.

frontend/src/components/ui/tabs.tsx

@@ -37,7 +37,11 @@ const TabsContent = React.forwardRef<
 >(({ className, ...props }, ref) => (
   <TabsPrimitive.Content
     ref={ref}
-    className={cn('mt-2 ring-offset-background focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2', className)}
+    // No focus ring on the panel itself. Radix makes the content focusable and
+    // moves focus into it when a tab is selected, so clicking anywhere in the
+    // lower half drew a full-width orange rule under the tab strip. The panel is
+    // a container — what it holds carries its own focus styling.
+    className={cn('mt-2 focus-visible:outline-none', className)}
     {...props}
   />
 ));